dynamic stamp missing

i have a custom dynamic stamp that i use in Acrobat Reader DC. (not the pro version). The stamp has been working for the last 2 to 3 years. Now suddenly it does not show up in Adobe reader. As far as i know i have not made any changes to my installation or the location of any files or settings. I tried removing and reinstalling the Adobe Reader application, but that does not help.  The dynamic stamp file itself is stilll located in the correct folder where it is has always been, but Adobe Reader just doesnt seem to do anything with it anymore. Any idea why my custom Dynamic stamp suddenly has dissapeared?? (windows update?? Adobe update??) attached the stampfile.