We just migrated from M1 to M2 and we had a lot of problems encountered on the way. I hope it is okay to post 3 questions here.
First, is the missing config price, all migrated config has missing price in M2. And we also found out that even if a new config is created and all necessary details are filled out especially the price, when we save it and edit again the price field becomes disabled and the price is gone. We need the price to be able to sync properly on ebay.
Second, is the adding of existing simple products manually to a config where the assigned sources of the simple products are removed once the config is saved. That is why we have to re import the qty again to the affected sku or just manually add the qty back to each sources.
Here's another example when we add simple but the attributes and quantity per source column does not display. Take note that this simple product has complete details and with sources assigned.
Third, is the missing order ids. We have a lot of missing order ids. In the image below we sorted the orders within same store view and they are many missing orders. We checked all our enabled payment methods however, none of those missing numbers has payment received.