Make sure that you don't have elements in your CAD file that are far away from your project area. TBC refuses to load the map if there are entities outside of the system boundary.
Blocks or sheet frames close to 0,0 are a candidate for this.
Zoom to drawing extends and press CTRL-A to select everything. Through the highlighting it's easier to see if there are widespread entities.
Unlikely that it is the issue in your case, but FYI have a look at my post #13 here,
------------------------------https://community.trimble.com/discussion/background-map-opening-issue#bmb83def10-ea1c-4803-a572-019526cfd146
Ronny Schneider
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