I made a post before on how villagers wouldn't accept a workbench after being cured, but after doing more testing they wouldn't accept them even when they were uncured. My trading hall is over 250 blocks away from my breeder, so I know that them being to close isn't the problem. After doing numerous different tests to see if one thing was the problem, I gave them beds to try that. When they had beds, they accepted the workbenches. So I removed the beds and then the workbenches but they still had their profession. I did not trade with them at all. After placing the benches down again, they would not take it. I placed the beds and then they did. They had the exact same trades as well. I removed the workbenches and they lost their profession. I placed them down again and the villagers regained them but with different trades, like normal. I did this test with multiple villagers including cured and uncured villagers and I got the same results. (I also noticed that I did not get a discount from cured villagers unless if I zombified them after I traded with them, I don't know if that is a bug or not)

    They accept workbenches with beds but not without. They also won't lose their profession without a bed. You have to break the workbench before the bed or they will still have their profession. The order of placing the bed or the workbench doesn't affect them at all as long as they have both. If you destroy the bed and then their workbench they will keep their profession, and if you replace the bed and the workbench (order doesn't matter) they will accept both but have the same trade. To change their trade, destroy and replace the workbench.