Path substitution problem

[nanouk76]

Hi all,
I may have stumbled on a very annoying regression with version 10.10.1 Previous functioning version was 10.10, I think. But let me explain my problem.
I am using Kodi on a CoreELEC TV box with the Jellyfin addon but not Jellycon. During installation of the addon, I chose native mode. On the Jellyfin server I had edited /var/lib/jellyfin/root/default/Films/options.xml (with Jellyfin stopped) from the command line (as it was no longer possible in the web GUI due to a previous Jellyfin server version change) and entered all the path substitutions that I needed. Everything worked as expected and I have been able to play my media fine until now.
However, I noticed a message about path substitutions during an automated update in Kodi. So I checked the options.xml file and noticed that all path substitutions had been removed. So I set about re-entering one NetworkPath after stopping the Jellyfin server and waiting for the processes to stop. After restarting the server from the command line, I opened options.xml and it had retained the modification.
But after managing the film library from the web UI, options.xml had again reverted back to a version without any NetworkPath lines. And I cannot play any file obviously.
Interestingly, the options.xml file with network paths survives a simple restart of Jellyfin from the command line.
Any help would be much appreciated as I had rather stick with native mode in the Kodi Jellyfin addon.
TIA