CK II - [2.8.2.1] [SAHQ] Temple vassal opinion from "How to Worship God" isn't working

[jonjowett]

One line summary of your issue
[2.8.2.1] [SAHQ] Temple vassal opinion from "How to Worship God" isn't working

Game Version
[2.8.2.1] [SAHQ]

What expansions do you have installed?
All of the above

Do you have mods enabled?
No

Please explain your issue is in as much detail as possible.
My previous character composed the book "How to worship God". This is supposed to give temple vassal opinion +10. However, this particular source of temple vassal opinion doesn't seem to be applied - it's not listed in the opinion tooltip for any of my vassal bishops.

NB: This was not fixed by exiting CK2 and reloading the save.

Steps to reproduce the issue.
Add the artifact "How to worship God" to your inventory.

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[jonjowett]

It seems this is a transient issue - I checked again 15 years later, and the modifier was applied correctly.

Uploading the current save, so you can see what's changed between the two.

 

[jonjowett]

...But the modifier is missing again after succession...