With Replace(3) - Match Case checkbox not saved

[russellgcummings]

Sirs,
The Match Case checkbox state (checked) isn't being saved.
Was it your intention to not save it?
Here is what I'm trying to change & it works fine with Match Case set:
CCJ_Show_03_31_18_Hour_1_Seg._1.mp3 -> CCJ-033118-H1T1.mp3
CCJ_Show_03_31_18_Hour_1_Seg._2.mp3 -> CCJ-033118-H1T2.mp3

I'm not using RegEx(1), because I don't understand how.
I tried reading the Regular Expressions Help page, but syntax didn't click in my head.
Could you help with saving Match Case or give me a hint to work with RegEx(1)?

Thank you,

Russ