TL;DR
imo, just turn off UseShoutCombo - otherwise ensure you're blocking the sub-spells correctly
you should just turn off shoutcombo (which is off by default due to conflicts this spell can cause).
but regarding the blocked spell - did you block the correct spell? since sometimes a spell that casts multiple spells, you want it to cast some but maybe not all - you need to block the subspells specifically.
your "but the effect is currently blocked." bit you actually snipped off the most important part - what actual spell is missing
you also didn't show the spell being blocked, so no clue what you're actually blocking
View attachment 70341
the FAQ has a spot specifically referencing that and how it can conflict with brells
View attachment 70342
> Issue with "Spiritual V" line blocking AtkHpBuff / Shout Combo <
TL;DR
imo, just turn off UseShoutCombo - otherwise ensure you're blocking the sub-spells correctly