It's working perfectly fine for me in KoboldCPP.
Check if you forgot to disable any other sampling methods, you have to disable everything and leave (Top-p at 1, Top-K at 0, Top-A at 0, Typ. at 1, TFS at 1, Seed at -1 and Mirostat Mode OFF) ONLY Min-p enabled (and, if you NEED, you can activate Repetition Penalty at 1.05~1.20 at maximum and I personally use RpRng. 2048 RpSlp. 0.9 but don't bother with these, only if you enable Repetition Penalty.)
Also, with Min-p, you should be using higher Temperature, start with Temperature at 1.5 and Min-p at 0.05, then you can finetune these two numbers at will, read the post to understand why.
Great, also, remember to always keep an eye on the KoboldCPP github for updates, I noticed that when you said two days ago that you were using 1.48 they already version 1.50 there.