Wrong subtitle chosen when preferred subtitle language unavailable

Hello,

I run LibreELEC 8.0.2 with Kodi Krypton 17.3 on a Raspberry Pi 2. Movie files are self-created MKV files. Subtitles are PGS streams (only forced part), if necessary. This is mostly English and German language.

If English subs are burned into the picture, I would only use the German forced subs for family members, that don’t understand English. (e.g. “13 Hours – The secret soldiers of Benghazi”). And here is a problem. In Kodi settings, I have set English as the preferred audio and subtitle language. When playing “13 Hours”, Kodi does not find the preferred subtitle (eng) and then shows the German subs.

This should not happen, as I can read the English subs in the picture just fine and the additonal German subs are rather distracting.
How can I make Kodi ignore non-preferred subs, if the preferred subtitle language isn’t available? I know about the “Language Preference Manager” addon, but that didn’t work in Krypton (yet). Are there maybe any XML hacks?

Andi