Issue here seems to be with the local client accessing the server. Following should be tried:

1. Try toggling Project Professional to an Offline state and then back Online. This will help re-sync the local cache status with the project status on the server. E.g. Right click on the bottom status bar  where it says Connected in Project and select Work Offline and do the same again and select Connect to Server. Note there is a built in delay of 15 seconds – so wait for about 15-20 seconds and then try the file open operation and see if the status reflects the correct state.

 

2. Close and relaunch project – Note there is a built in delay of 30 seconds – so wait for about 30 seconds and then try the file open operation and see if the project status reflects the correct state. E.g. is it still showing up as checkin pending?

Incase the above doesn’t work continue with the following:

1.        

2.        

3. After launching project professional, click on Tools in the top menu bar.
4. Point to Local Project Cache and then click on Cleanup Cache

 

5. Highlight the listed entries in ‘Remove projects from cache’ section, one by one and click on the button ‘Remove from cache’

 

 

6. Kindly toggle the project filter and perform the above mentioned (step#3) to make sure that all entries are removed.

There could be other factors due to which that cache status will appear. Make sure that the queue is clear and the project workspace is intact.