Just putting this out there so others can find this fix.
I opened up my project this Morning and I could Rotate and Scale objects using the gizmos but I could no longer translate objects (Grid snapping was not on).
Also the foliage tools stopped working. I no longer got a green sphere to manually paint single foliage meshes or the blue sphere to paint using the foliage brushes.
After some extensive googling the bug someone had found was that the “Near Clip Plane” value was set too low. Mine was set to 0.0001 to fix an issue where the camera was super close up on some foliage. I do still want a low “Near Clip Plane” but I also want to work. So I set it to 0.1 and re-started my project. I can now translate my objects again and the foliage tools now work.
Very weird bug, I don’t know if anyone can re-create it but it would be good to get fixed or have a limit to the smallest value you can put in the “Near Clip Plane” so this doesn’t affect others.
Cheers!