Has this been happening for a long time? During development I did notice that sometimes the information in the test account I use would occasionally take a couple of days to update, but I never payed too much attention to it.
Anyway, I will take a look at it more closely.
You could try adding that snippet about delaying app measurement initialization and see if it makes any difference. You would need to make an export for an Android Studio project, edit the manifest file and then make a build from Android Studio.
That is what I will try doing, but you don't need to wait for me, if you have Android Studio you can try it out yourself.
The documentation you linked talks about user consent, so maybe if no consent is given, measurement never starts? I am just guessing, will need to try it out to see for sure.