Incorrect behaviour of "Delete files" button

Note: Does not always reproduce

"Delete files" request does not delete the file.
Delete request returns "Cannot delete uploadDefinition 09ef7415-34e4-44cd-9af3-31953df9f200 - linked files are already being processed".

Steps to reproduce:

1. Login into https://folijet-perf.ci.folio.org
2. Start importing a file of 500-1000 records
3. Without waiting for the end of the previous DI to immediately start the next DI
4. After the 2nd DI start click on the "Delete files" button

"Delete files" is available, but does not work after all DIs are complete. 

Request: DELETE https://folijet-perf-okapi.ci.folio.org/data-import/uploadDefinitions/09ef7415-34e4-44cd-9af3-31953df9f200

Response: Cannot delete uploadDefinition 09ef7415-34e4-44cd-9af3-31953df9f200 - linked files are already being processed