Loading saved HotA HD TCP/IP game

So I installed HoMM3 Complete Edition + HD mod + HotA and played a random TCP/IP multiplayer map with my kids. Everybody enjoyed, until we had to stop and continue the game afterwards. The bummer is that when I tried to load the saved games I discovered that it's not possible to do in HD version.

The saved games are visible in the loading screen, and I can even load them in either the 'single player' mode or from a non-HD HotA executable, but in 'multiplayer' HD the 'Load' button is disabled.

The saves appear in one of the 'HotA Random' subdirectories, with '.GM3' extension.

Is there any setting I need to activate so the loading will be possible? Or is it a known problem/limitation?

My thanks go to any kind soul who can help.