no worries, let me turn off your ext and try again.
EDIT:
with Extended automation and overlays, and PF Effect Removal off:
STACK: DEX: -2
added multiple time to a creature with no effect
Attachment 52678
So I think this is something with BCE and another EXT. will load up BCE by itself and try things later...
Edit 2:
So I loaded a test PFRPG server and BCE is the only ext (I turned on a few library items to make things easy)
DEX:[-1d2]
does not work
DEX:-2
works but does not stack (normal)
STACK: DEX:-2
can be added to the same creature multiple times BUT the DEX:-2 is not working
tested at this point with the photo below, then added an AC-5 to just make sure the DEF EFFECT was showing (see the pic below)
Attachment 52679
Hope that helps (and hopefully I am not just making a mistake and all this is unneeded)