Unknownreported this bug
00:00 ~ 00:06 : mythicmobs 5.2.0 06:00 ~ 00:12 : MythicMobsPremium-5.2.5-SNAPSHOT
NoDamageTicks option are set "4", but it looks like "1" or no limit. only difference is mythicmobs version.
I reported bugs at #1049 , when player returned to the chunk, the problem that monster's health was fully charged has been fixed, but the damage interval is still set very short.