RE: Dynamics GP Migration Tool
Hi Joe,
I'm not familiar with the construct of the GP export (the columns, order of columns, etc.), but if you are using the Microsoft created extension to import data from GP, you will need to download the template from Business Central's Data Migration wizard (after selecting GP as the import source), populate it, and then upload that file.
If you use the search functionality to navigate to the Data Migration Overview page, you might be able to see an error message / status on the file you tried to upload, but even if you don't, I wouldn't spend a lot of time on that. It's not likely that the column layout of that csv file is consistent with what Business Central's template has.
Also, in my experience, the GP and QuickBooks imports that Microsoft's extensions offer are not comprehensive. As a consultant, I would recommend you to consider using the Configuration Packages (RapidStart) in Business Central. Here, you can bring data into more tables and fields, including open AP, open AR, etc.
I hope this helps. If my response has answered your question, please verify by clicking Yes next to "Did this answer your question?"