Took me a while to realize that when there are wraiths during a ground mission, I always get an alien turn that never ends.
This only occurs when 1) there are wraith enemies and 2) when my team is near or entering the grounded cruiser. My team fights it's why up to the cruiser during the mission with no problem, even encountering and killing a wraith or two away from the ship.
I can only guess that the issue is related to a wraith trying and failing to teleport. I hear doors slide, sometimes the psionic attack sound (typical alien turn sounds), but the alien turn never ends.
As my own personal workaround, if I discover a wraith on a ground mission, I reload to an earlier save (after the aerial battle but before engaging the ground mission), and then airstrike the site rather than intercept. Because it ALWAYS eventually happens when I get near the ship. If no wraiths, then I can engage and complete the ground mission.
It's always been a cruiser, but I have not encountered larger ships yet, so it may occur on those as well.
I use a few mods that I will list in order below. Maybe they are related to the problem. I also play through Steam.
Delux Geoscape Cheat Mod (yes, I am a wimp at games)
Enhanced Crash Sites
Khall's More Portraits
Steel Gonad's Names of the World
Lore +
Instant Grenades
Khall's Tundra Tilesets
and of course the three parts of the X:CE .33HF2 mods