Here are the items you asked for:
1. Complete Grid code example(both in server and client side).
(See Attached Zip file)
2. Are you facing the issue while applying the filter to string(text) column alone or all the available column?
The export only appears to fail when a column is filtered to exclude (not equal to) a text value. When there are no filters or when the filter is to include (equal to) a text value the export works. (See attached screenshots in zip)
3. Screenshot/Video demo along with replication procedure to reproduce the issue at our end.
See attached screenshots in zip
4. Stringified model of the Grid on server side while on Exporting as like below screenshot and copy it into clipboard.
Not sure exactly how to do that, but I made a csv of the exported Watch variable DeficienciesGrid.Model (In attached zip)