What steps will reproduce the problem?

1. Enable ora3 Combat Alerts for Missed Interrupts and enable the module for "World"
2. Try to interrupt a noninterruptable spell (e. g. Rebuke cast by Stormbound Conquerors in Zuldazar: Warport Rastari)
3. No missed interrupt message is shown in chat

What version of oRA3 are you using?

v8.1.1-1-g43cbeec

Do you have an error log of what happened?

No, as expected. The feature simply doesn't seem to consider this case.

Please provide any additional information below. (example: localization of your client if not enUS or enGB)

As far as I can tell from a simple look into the relevant code block, there's just no handling for this case. I.e. the "InterruptCast" case simply returns as long as the target unit is casting, regardless of interruptability of the cast and no SPELL_MISSED event is generated in this case to handle this in a different handler.

To elaborate on why I'd appreciate at least an option to show such "misses":
During our latest mythic Jaina kill, one of our assigned kickers completely dropped the ball and simply didn't try to interrupt the Nova cast at all, while the second player assigned to this specific cast did use their interrupt spell, but on Jaina herself, who just so happened to be casting her uninterruptable "Orb of Frost" cast. Sure, checking logs would also tell you this, but why not have it easily available via chat message?