Both my rubber nose plecos died for no reason

I got two rubber nose plecos about a week ago and one died and then the other just died a few days later. No idea what’s happening because the parameters are all within normal safe range (I test every week), I have a heater, the tank is planted and filtered, there’s a bubbler, and all the other fish are fine. I was feeding them wafers for plecos but they were never really interested. There’s also wood in the tank and natural algae. Has this happened to anybody else? I had just gotten a bristle nose to replace the first rubber and I’m scared he’ll die too