5e Charactermancer Refusing Level+

I've been playing a custom subclass (Way of the Astral Self) for Monk in a 5e game. Today I went to level up using the charactermancer and instead was greeted with an error message and the inability to start the level up process via charactermancer. The error message is as follows: " ATTENTION - You cannot launch the charactermancer level up until you have a class, level, and HP set for level one. Please run the charactermancer creator first. The level up tool doesn't work with custom classes or if the multiclass options are set up incorrectly." I've been playing this character for over a year now and have used " charactermancer level + " to level them and have never run into this problem. Has something changed with the charactermancer recently or is this a legitimate bug?

I am not sure, but I am having the same problem with one of my players. He is unable to level his warlock despite having just recently leveled it.

I have the same error message on a copy of a Sorcerer who is not custom or multiclassed, though he's in a test game and I might have messed around with him. I clicked Level+ anyway and it leveled up just fine. What happens if you click the button?

The Attribute leveler_warningflag seems to control this warning. If set to show it will display that warning, but I don't know what actually triggers it. The Attribute does not seem to exist until it has been triggered. It doesn't seem to actually prevent the charactermancer from running though? I believe whatever is causing the warning to appear is a bug, the character it happened to in my test game (Sorcerer) had a standard class, level and HP. There's nothing about the character that's leaping out at me as any different from the other, unaffected, character sheets.

It seems the issue for my instance was that my HP maximum was deleted and all I had on my sheet was current HP.