I agree with - I am always hesitant to upgrade to the latest version. It fixes one issue but it also breaks two others. This is exactly what happened in our case. We were having Field Match issues in the alarm when we were using 9.4.2. Support told us that this issue is fixed in 9.5 MR4 - We upgraded and it fixed the field match issue but then it also broke a few other things which was working earlier.
MR6, however, has a lot of fixes. It was released to support this week. I will be upgrading my lab's SIEM to the latest version and test.
As a side note, Jonarmani, we have seen the same results where some alarms send out emails during non business hours and then they stop during business hours