Metagrid Pro 6.0.1 - cannot finalize Reaper integration

I follow instructions inside the app, but still integration status is shown as “incomplete” and Reaper as “not running” even though session is opened.
I’ve been using Metagrid Pro for a long time and when switched to Metaserver 5.x.x with Loop MIDI everything is working back again.

REAPER 7.74
Win 11 Pro x64
CPU: Intel i9 12900 KF
RAM: 128 GB DDR 4
GPU: RX 6600 XT