Gpx-files in shared folder cannot be opened in GPXPOD

i have a folder containing gpx-files that is shared (read-only) to a group of nextcloud-users. no group-sharing or anything else is installed; the group contains only local nextcloud-users.
the users can “see” and “open” the folder and “see” and download the files, but gpxpod cannot display them - when the file is directly clicked on or opened in gpxpod via the three dots gpxpod states “no gpx-file found.”
When gpxpod is opened w/out any files it cannot find the folder/files.
Is there any way to fix this?
THX for your input!

(nextcloud-version is 15.0.7 on debian-stretch; no other issues)

It seems that this issue has already been reported.

you are right, thank you!
i did not look there. hope they’ll find a solution.