While adding Flat files to PixInsight's WBPP this evenng I noticed a number of files are missing the FITS header  "Filter" entry.  16 of 50 Green files were missing the keyword, 11 of the Blue also. (haven't done the others yet...). The order isn't the same in each case.  I can add the keywords but it's time consuming.

Any idea what's happening?  The log file seems to indicate all is proceeding as expected.  
KStars 3.5.7 Stable, Build: 2022-01-24T09:12:30Z on Kubuntu