Collapse Transformation on my Precomp reveals a trackmatted layer although it shouldn't

I'm using adobe after effects CC 12.0 on a windows machine.

I've checked and I'm having this problem also on after effects cs6 11.0 (different machine)

this problem does not occur on after effects CC 12.2

my problem is that I have a composition with a precomp that contains a layer using

a Track Matte solid with a mask that is revealed from top to bottom.

when I move the precomp forward in time in my main composition and press Collapse Transformations

for the precomp, the layer that is supposed to be masked first and then revealed from top to bottom

reveals itself although it shouldn't just yet, as if I am looking forward in time in my precomp.

this happens only when I use a track matte instead of masking the layer itself.

and if I take the Precomp and move it to the start of my composition

it works just fine even when collapsed. but only after I purge all memory.

if I move if forward in time again it works fine but if I uncollapse and collapse again

and clean the cache - it causes the same problem.

my question is:

is this a bug? or am I missing something here?

since this is hard to explain

Im attaching a project file with similar situation to make it clear

and also attaching 5 jpegs to further illustrate the problem.