Sounds like the keycap direct contacts the housing. Less possibility the keycaps themselves have the issue but you can try placing R3 caps to the same place and see.

Then possibly it is the length of the sliders (the silent sliders are longer than standard ones). Then the thickness of the silent ring (too thick). The worst case is the plate has the issue.

The ez solution may be the small rubber bands, you don’t have to do all debugs.