So you are not having trouble saving the BIMx file, it is the BIMx program just showing the loading progress?
Does it stop or are there any error messages?
Can you open BIMx without opening a file?
Can you open other BIMx files?
Can you crate a simple BIMx (say just 4 walls) and open that?
I am thinking that there is something in your model that BIMx doesn't like.
One of the forum moderators.
Versions 6.5 to 25
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10