Yesterday I had an Eneloop Pro battery venting gas inside my flash. Consequently, I had to use a tool to open the battery compartment due to overpressure inside. When placing all four batteries in a smart charger it indicated that one of them was completely discharged. No visible signs of anything wrong.
I have used various Eneloop batteries since 2010, and never before had any problems.
Considering how popular Eneloop batteries are among underwater photographers I was surprised to read that Panasonic clearly states they should not be used in airtight appliances - because they may release hydrogen gas if misused:
Link to Panasonic Q&A. Scroll down a bit.
Have anyone else experienced Eneloop batteries venting gas?