If you crashed or did not exit the file properly form your last session of AC then AC thinks that you are still in the file. As long as you know that you do not have multiple sessions of AC running and you are not actually in the file you should be able to "Open with Exclusive Access" without any problems.
David Larrew, AIA, GDLA, GSRC
Architectural Technology Specialist
a r c h i S O L U T I O N S
WIN7-10/ OSX 10.15.7
AC 5.1-25 USA