'Uploading...' XLS decision table never finishes

Description of problem:
After filling in the 'Create new' dialog and submitting it, 'Uploading...' progress dialog appears and hangs there forever.

After signing out and in, the uploaded XLS table can be opened and contains the uploaded file. The hanging dialog seems to be the only issue.

Version-Release number of selected component (if applicable):
DR5

How reproducible:
always

Steps to Reproduce:
1. navigate to uf-playground.git / mortgages / Resources
2. choose New > New Decision Table (Spreadsheet)
3. fill in name and file path, click OK

Actual results:
'Uploading...' progress dialog running forever

Expected results:
The upload process finish should be indicated by hiding all the modal dialogs.