How to say that a problem has occurred previously in passive voice
Well, if you really want the Passive transform of
- People must have had this problem in the past
here it is:
- This problem must have been had in the past by people
which is grammatical English -- people would understand it if you said it,
but not colloquial English -- people might think askance at you if you said it.
Generally the agent phrase by people would get deleted -- it's indefinite to start with, after all.
This leaves
- This problem must have been had in the past
and that is just poor because the idiom is have a/the/some/... problem.
That is, there isn't any real have-ing going on; there is problem-ing instead,
but English doesn't have a verb for that, so we use a construction with the light verb have.
There are many:
- have a baby, have a fit, have a drink, have a problem, have a headache
And moving problem to the other side of have,
and adding an extra auxiliary have by using the Perfect,
and then adding an extra auxiliary been by using the Passive
obscures the idiom, and simply makes it way too complex.
The point of Passive (or any other construction) is to make an utterance more clear.
Not less.