I suspect your problem is that the hole has been wallowed out maybe by removal and reinstallation of the pin. Unfortunately the hole in the lower is the hole that interferes with the pin holding it firmly in place or to put it another way, replacing your bolt stop will not help. If a new pin does not solve your problem try a 3/32 Cotter pin. I have used them for this application in guns I intended to strip later. Much easier to get a Cotter pin in and out than a roll pin. Use a 3/32 roll pin on the trigger guard too, for the same reason. Anyway, the 3/32 Cotter pin will for certain hold your bolt stop in place. It does not look right but it does work. I have done this with 8 lowers, a thousand or two rounds each, no issues.
Reason I did that, I bought several lowers but only had one LPK. I wanted to test all the lowers but had to move the LPK from lower to lower. I used Cotter pins in place of roll pins.
I’ve seen threaded bolt stop pins used on some billet lowers. Maybe retrofitting one of these might be a solution if the holes in the lower do turn out to be buggered?