FF cache not being deleted

[circe801]

v5.22.5724 (64 bit)  on windows 10 home anniversary update

i've not encountered this problem before in my approximately 20 years of using ccleaner--even though 'clear browser cache' is checked in both ccleaner AND firefox v49.0.1, when i run ccleaner, it shows a FF browser cache file to be deleted (which shouldn't happen, as FF is set to clear this upon close), but when i run the cleaner, it shows 0 bytes of that cache as deleted--it is all still there.  and why is it showing as a 'file to be deleted' if ccleaner isn't then deletng it?

any suggestions??  i mean, why is it even there after closing FF--FF cache not deleted then, ccleaner won't delete it, either.

i find this odd.

 

thanks!!