POWER APPS EXCEL DATA IMPORT FEATURE IS B-R-O-K-E-N..... PLEASE FIX THIS MICROSOFT!!!!!!
Solved - see below..........
Steve Pucelik from Microsoft gave me this solution after I spent 2 weeks of getting nowhere, and literally countless hours looking for help from people here, and from MS Tech Support.
1. Once the excel file is imported into Dataverse thru Power Query - be sure the Dataflow ran, and finished updating.
2. After importing the data into Power Query (while in Power Query) - be sure all columns are selected (just click on the choose columns button to be sure all are selected), and click on the "use first row as headers button"
3. After next, Under column mapping - keep the "Unique Primary Name Box" as "auto-generated", and give the "Name Column" box a unique name not matching an existing column name - something like "primarykey". Under Load Settings, Select the "Load to new table" radio button, and give the table name and table display name boxes names you'll recognize later in the custom table list. Next - Refresh manually if you want, and then create.
4. Refresh the browser
5. Go in to Dataflows right away - find the flow with the Next Refresh still in Progress. Rename it to something that links it to the table it is connected to (this should be done automatically by Power Apps - but it is not). I name it the same as the table name. Of course, you must wait for the flow to finish it's initial refresh before you go on.
6. Back to Tables - under custom tables - find the table you just created.
7. Now go to Views - Select Active-TableName .... Pick the Active view of the table
8. On the left - click on the columns names to add them to the view
9. In the top right - hit save, and then publish.
10. Go back to the Data > Tables in Power apps, for the table you were just working on.
11. Click on the Data menu item (lower one to the right of Keys) - select refresh data at the top below the purple banner - and refresh the data - (you may not need to do this).....
12. All of the columns and your original data in the excel file will be there.
BIG THANKS TO STEVE PUCELIK AT MICROSOFT FOR SOLVING THIS CONUMDRUM!