A particular file refuses to synch, Linux Desktop Client

I have a set of files in a Nextcloud subfolder, in particular ‘Gramps’ backup files in .gramps and .gpkg format.

When I run my backup script, I rotate the existing files x.gramps and x.gpkg to x.gramps.0 and x.gpkg.0 with savelog then recreate them using gramps command line export. All files synch to Nextcloud, except the new x.gramps gets ‘left behind’ and I need to drag’n’drop x.gramps onto the Nextcloud web folder to upload it manually. This is consistent over several iterations - all of the files created by savelog and x.gpkg are uploaded properly, just this particular file is ‘lost’ to Nextcloud.

Does anyone have any clue why, or how to trigger (touch?) the file to ensure upload?

─greg@hermes:~
└─$ ll -h Nextcloud/Documents/Genealogy/New*
-rw-rw-r-- 1 greg greg 405M Nov 27 11:48 Nextcloud/Documents/Genealogy/Newton-McNamara_hermes_backup.gpkg
-rw-rw-r-- 1 greg greg 401M Nov 25 17:10 Nextcloud/Documents/Genealogy/Newton-McNamara_hermes_backup.gpkg.0
-rw-rw-r-- 1 greg greg 344M Nov 25 13:44 Nextcloud/Documents/Genealogy/Newton-McNamara_hermes_backup.gpkg.1.gz
-rw-rw-r-- 1 greg greg 406K Nov 27 11:48 Nextcloud/Documents/Genealogy/Newton-McNamara_hermes_backup.gramps
-rw-rw-r-- 1 greg greg 405K Nov 25 17:10 Nextcloud/Documents/Genealogy/Newton-McNamara_hermes_backup.gramps.0
-rw-rw-r-- 1 greg greg 404K Nov 25 13:44 Nextcloud/Documents/Genealogy/Newton-McNamara_hermes_backup.gramps.1.gz