I reinstalled 2.9 Modular version according this thread, but I'm wondering that Server cannot start all maps? It says in the description:
"Terrain and WWII units modules don't need activation when launched in server mode without rendering, server owners shouldn't buy them. "
It seems that Sinai map does not follow this rule. Other terrains can be started, but Sinai missions are greyed out. Actually the reason seems to be that the Dedicated server has not downloaded any stuff from Sinai to Mods\terrains folder.
----- EDIT -----
Ok, when I manually copied Sinai Folder from OpenBeta installation I can now start it. But still, something to look at.