When trying to level up glowstone crops, the offspring do not grow, and do not drop seeds if broken. The player-planted parents grow fine. (EDIT: i'm having the same problem with other resource plants, so the problem is not limited to glowstone.)
using:
agricraft-2.0.0-0.6.0-a10
Forge 12.18.3.2221

That may be the case, i will test when i have the opportunity later today. EDIT: You were correct in your assumption, but the plants spreading to regular crop sticks is a bug that needs to be worked on :)

Did they transfer over to Cross-Sticks or regular Crop Sticks? I've noticed that sometimes they like to 'expand' to regular crop sticks when they shouldn't, with WAILA saying 'This plant can not grow here' and the plant not dropping anything when broken. Generally works fine with Cross-Sticks, at least that I've noticed.

Yeah. I thought I saw it reported a while back, but I might be mistaken...

It looks like ghost plant being spread. The spreading code was messed up so that an actual spread event was far rarer than it should have been.

Consolidated to #863