Buffer size not correct, hangs Pianoteq 8 (7 is ok)

Linux Fedora 37, Pipewire, Reaper 6.71

Short version :
Pianoteq 8 loads in Reaper with an incorrect buffer size, wheras Pianoteq 7 is correctly launched.

Long version :
Sometimes, Pianoteq 8 loads without the correct buffer size, and it is impossible to change it, nor in Reaper parameters. As soon as I play a note, an awful noise is ringing and stands.

I use Pipewire only (no Carla or whatever Jack Client) and have no possibility to change audio parameters in Reaper : I launch Reaper with buffer size set up to 256 in a terminal command line.

Pianoteq 8 ends up up with 1024 Buffer size. It seems to happen only when I don't use my usb audio interface : just the laptop. But it doesn't happen with Pianoteq 7, so I suppose it is a Pianoteq 8 error.