Villager that are on a space of 1 x 1 cannot acquire a new jobs, unlike Villagers on Minecarts or boats, for example.
Also, If you get a Villager with a Job on a 1 x 1 space and destroy it's working station, he will go back to unemployed but won't happen so the other way.
Steps to Reproduce:
1. Make a station for Villagers with no more than 1 x 1 of space.
2. The Villager inside cannot acquire any new job.
Look at the picture.
Please check if that's still an issue for you in the latest 1.14 (pre-)release.