I intentionally stuck road vehicles and observed them for 18 months. None of those stuck vehicles alert with tooltip and popup messages. Just wait for clearance forever.
You can get this saved game from here (https://drive.google.com/open?id=1xOxNLL8eR3xt6BJE-2og3exWCXic-EVD).
Thank you for the report and reproduction case - I believe that I have now managed to fix this.
I should be grateful if you could re-test with the next nightly build.
I have confirmed that those stuck vehicles will show the stuck the following month. (Once again created the same situation from the beginning)
Thank you for fixing it.
Splendid, thank you for confirming.