Thanks for your bug report. I do not use ZNC - can you provide more information? For example, if you use "/debug on" to enable debugging output to a debug.log file, and compare the debug.log files for 1438 vs 1897, do you see any differences?
Okay, I have found the cause of this issue. This will be fixed in the next beta. For the time being, I have removed beta 1897 from the beta post as this bug affects a number of features.