UPS Error, loads rates but is never available for the customer

[kuwiano]

I am using the magento 2 preinstalled UPS Module (Austrian shop).

My credentials (from UPS) are correct and valid for production.

I get this Error: 

Spoiler

This shipping method is currently unavailable. If you would like to ship using this shipping method, please contact us.This shipping method is currently unavailable. If you would
like to ship using this shipping method, please contact us.

Using UPS XML, I get this request / response I send/get to/from UPS:

array (
  'accessRequest' => '
<?xml version="1.0"?>
<AccessRequest xml:lang="en-US">
    <AccessLicenseNumber>****</AccessLicenseNumber>
    <UserId>****</UserId>
    <Password>****</Password>
</AccessRequest>
',
  'request' => '
<?xml version="1.0"?>
<RatingServiceSelectionRequest xml:lang="en-US">
    <Request>
        <TransactionReference>
            <CustomerContext>Rating and Service</CustomerContext>
            <XpciVersion>1.0</XpciVersion>
        </TransactionReference>
        <RequestAction>Rate</RequestAction>
        <RequestOption>Shop</RequestOption>
    </Request>
    <PickupType>
        <Code>01</Code>
        <Description>Regular Daily Pickup</Description>
    </PickupType>
    <Shipment>
        <Shipper>
            <ShipperNumber>**VALIDSHIPPERNUMBER**</ShipperNumber>
            <Address>
                <City>**VALIDCITY**</City>
                <PostalCode>**VALIDPOSTAL**</PostalCode>
                <CountryCode>AT</CountryCode>
                <StateProvinceCode>OO</StateProvinceCode>
            </Address>
        </Shipper>
        <ShipTo>
            <Address>
                <PostalCode>**VALIDPOSTALCODE**</PostalCode>
                <CountryCode>AT</CountryCode>
                <ResidentialAddress>02</ResidentialAddress>
                <StateProvinceCode>OO</StateProvinceCode>
            </Address>
        </ShipTo>
        <ShipFrom>
            <Address>
                <PostalCode>**VALIDPOSTALCODE**</PostalCode>
                <CountryCode>AT</CountryCode>
                <StateProvinceCode>OO</StateProvinceCode>
            </Address>
        </ShipFrom>
        <Package>
            <PackagingType>
                <Code>00</Code>
            </PackagingType>
            <PackageWeight>
                <UnitOfMeasurement>
                    <Code>KGS</Code>
                </UnitOfMeasurement>
                <Weight>0.1</Weight>
            </PackageWeight>
        </Package>
        <RateInformation>
            <NegotiatedRatesIndicator/>
        </RateInformation>
    </Shipment>
</RatingServiceSelectionRequest>',
  'result' => '<?xml version="1.0"?>
<RatingServiceSelectionResponse>
    <Response>
        <TransactionReference>
            <CustomerContext>Rating and Service</CustomerContext>
            <XpciVersion>1.0</XpciVersion>
        </TransactionReference>
        <ResponseStatusCode>1</ResponseStatusCode>
        <ResponseStatusDescription>Success</ResponseStatusDescription>
    </Response>
    <RatedShipment>
        <Service>
            <Code>65</Code>
        </Service>
        <RatedShipmentWarning>Your invoice may vary from the displayed reference rates</RatedShipmentWarning>
        <BillingWeight>
            <UnitOfMeasurement>
                <Code>KGS</Code>
            </UnitOfMeasurement>
            <Weight>0.5</Weight>
        </BillingWeight>
        <TransportationCharges>
            <CurrencyCode>EUR</CurrencyCode>
            <MonetaryValue>50.62</MonetaryValue>
        </TransportationCharges>
        <ServiceOptionsCharges>
            <CurrencyCode>EUR</CurrencyCode>
            <MonetaryValue>0.00</MonetaryValue>
        </ServiceOptionsCharges>
        <TotalCharges>
            <CurrencyCode>EUR</CurrencyCode>
            <MonetaryValue>50.62</MonetaryValue>
        </TotalCharges>
        <GuaranteedDaysToDelivery>1</GuaranteedDaysToDelivery>
        <ScheduledDeliveryTime>11:30 P.M.</ScheduledDeliveryTime>
        <RatedPackage>
            <TransportationCharges>
                <CurrencyCode/>
                <MonetaryValue/>
            </TransportationCharges>
            <ServiceOptionsCharges>
                <CurrencyCode/>
                <MonetaryValue/>
            </ServiceOptionsCharges>
            <TotalCharges>
                <CurrencyCode/>
                <MonetaryValue/>
            </TotalCharges>
            <Weight>0.1</Weight>
            <BillingWeight>
                <UnitOfMeasurement>
                    <Code/>
                </UnitOfMeasurement>
                <Weight/>
            </BillingWeight>
        </RatedPackage>
        <NegotiatedRates>
            <NetSummaryCharges>
                <GrandTotal>
                    <CurrencyCode>EUR</CurrencyCode>
                    <MonetaryValue>11.20</MonetaryValue>
                </GrandTotal>
            </NetSummaryCharges>
        </NegotiatedRates>
    </RatedShipment>
</RatingServiceSelectionResponse>',) {"is_exception":false} []

I played around with the settings, but couldn't get it to work.

• products have correct weight associated (0 < weight < 150)
• origin is set correctly
• only flat rate (shipping) is activated everything else is deactivated
• tried with both testing / production env and it is not working
• does work if I change my origin to us (and units to LBS)

Another quick question: I read somewhere that label printing is only available for US, is this true and if yes are there any alternatives for UPS that any country can use? Did I miss any obvious basic configurations?