Detail #48: Some congruence blocking things

I considered making a few suggestions along the lines of "no congruence for interrogative pronouns" and so on, but changed my mind a bit.

Let us imagine a language where there is an explicit congruence marker for every person, and there is a specific present tense stem (or a full-on lack of infinitives or anything like that; let us assume there's little to no way of confusing the congruenceless verb from an infinitive). Now, we could come up with a lot of relatively easy kinds of things I have already probably hinted at, here ordered by abstractness:

• certain specific pronouns (interrogatives) or 
• certain lexical items
• certain null-subjects
• indefiniteness
• aspect-like things

However somehow, all these things seem rather similarly complex - all the suggestions this far are in a way rather focused on one particular constituent or semantic idea. Let us try and step a bit out from the verb phrase / clause, and consider interactions between participants and actions on a more general level, some more pragmatic stuff perchance.

How about

• distant past combined with either lack of tangible results, imperfectiveness or non-differentiable objects
• uncertain future or present combined with indefinite object
• speaker having distinct lack of enthusiasm for the reported information
• past-known-by-hearsay combined with intransitivity
• partially or entirely repeated speech?
• certain specific groups of verbs under circumstances specific for each group