By any chance was it workijng for about 70 days. AFP is a Priced software on the ISeries. It will work for 70 days but without a license code will stop working. Check QSYSOPR messages arounf that time or History to see if you had License errors,
AFPDS spooled files can be created and viewed without license.
There are features that may be licensed, but the basic viewer shouldn’t be affected as long as AFPDS spooled files are still being created.