When I set the uses:-tag of an villager to 1 or higher, I will unlock new not-custom trades. It should not, because it should only unlock new trades, if I trade a "new" trade; new trades (custom or not) have a uses:-tag of 0. If I set it to 1, it isn't 0, so the villager should think, I've allready traded with him. Here is a /summon command for example:
/summon Villager ~ ~1 ~ {Profession:4,Offers:{Recipes:[{buy:{id:iron_ingot,Count:1b},sell:{id:cooked_beef,Count:1b},uses:1}]}}
PS: I've allready created an issue for this bug. It sais, it is resolved, but this bug wasn't be fixed. The link:
You didn't read MC-48929, did you ?