The DOT issues with the talents "Scion of Flame, Heart of the Storm, Spirit of Decay and Secrets of Rime" have not yet been fixed. You can find information about this here, regarding a patch made some time ago, but this patch currently cannot be used with the current version:
https://forums.obsidian.net/topic/93221-community-bug-fixes/
I’m not sure, but I think the problem with these talents also applies to some class spell or item.
You also have these mods that fix some bugs that haven’t been corrected yet either:
https://www.nexusmods.com/pillarsofeternity/mods/385
https://www.nexusmods.com/pillarsofeternity/mods/384
https://www.nexusmods.com/pillarsofeternity/mods/377
https://www.nexusmods.com/pillarsofeternity/mods/371 -> I think this one fixes the DOT issue with the talents mentioned above.
Maybe not all of these mods are actually bugs for you, I’m sharing them so you can take a look and consider whether it’s worth fixing or changing the behavior of the spells they adjust, for example.
I think the DOT bug with the talents (and as I said, I believe it affects more than just those 4 talents) is quite important, because one chooses these talents to increase the DOT damage of spells/abilities of those elements. So, if you use a particular spell as your main damage spell and want to get this talent to boost its DOT damage, it’s useless because it doesn’t work. I think it’s crucial to fix this already.