By saying "shut down properly" this means "File/Exit" from the pull-down (Windows version) or equal process on the Mac. Don't just click the "X" button (Windows version).
Also, be sure you do not have more than one session of AC open at that time.
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