Ok, I've checked it with Powerapps Plan 2 and the issue still occurs. It's getting more and more annoying, because I'm stuck with my project and Support adviced me to get a new license and it didn't help anyway.
@sabinn - what is the deal with this??? No-one has said anything on this and remains an issue including in Chrome.
Thank you @sabinn - org id for the one I'm trying to use the "Get Data from Excel" import service for is 1d48e593-97f1-4555-a5d1-ef5ee8759979
Please let me know if you need any more info.
Update: We diagnosed this on our end and I believe we may have found the issue. Allow us to test a couple of more things and I should be able to provide an update tomorrow.
Appreciate your patience.
Update: We have successfully diagnosed the issue and currently in the process of fixing it on our side. We will try and deploy the fix at the earliest. However, please be informed that it would still take a few days for it show up in your region. I would try again mid to late next week.
Once again - Thank you for reaching out and reporting the problem
I was able to get past the previous error message. It appears to be working now but I don't want to overwrite my data so I did not complete the import for a full test.
Still doesn't work for me. I have created an entity "Salesmen" and tried to import data from file containing many data tables and I have got an error message with the whole call stack. When I tried with an one-sheet xls file, I got something like this: "The file could not be uploaded for Salesmen: The project does not exist: DMImport_2018_10_10T07_31_18_064Z.".