You can queue the alchemy room as the first room and then use an incredibly large reward item combination in the reward queue, e.g. 9999 mage books. It'll then handle the alchemy room until out of resources.
I was unable to reproduce this issue. Were you using a proxy on the account? Are you still encountering this issue?
Feel free to reply to me via Discord if you prefer as well.
Are you positive that you did not accidentally choose too high of a hitpoints to eat at, causing it to always trigger eating?
If not, please send me a message on Discord.