Ran into this problem tonight. First issue with the msfs beta since I started using it a few months ago. I will note that I did not try this in another aircraft yet, just the latest flybywire A32NX dev version. Creating a flight from LOWI to LIEO with the following flight plan
MOGTI DCT XEBIX Y740 ATPED M984 LUSIL DCT SRN M858 TORTU UM858 AJO UM733 CORSI
The sim would freeze for at least 30-60 seconds (thought it crashed the first time) when importing a simbrief plan with the aircraft. Went back and tried a manual entry and the section “SRN M858 TORTU” is responsible for the temporary hang (can’t hit the ESC menu, move camera, nothing). I removed the beta install of the data and there were no issues with the same route.