Regression - Unable to "save & close" any edited document

1. Login to CMS as any user
2. Navigate to documents >> open any document & edit
3. After edit - click "save & close"

Expected - The document should return to view mode, showing a diff on recent changes
Actual - Hippo reload icon runs - the document remains in edit mode.

Note - This issue is not occurring always but frequency is often. I faced similar issue yesterday evening - today morning it was working fine, now it is back!