SolveSpace tells me I have 2 Degrees of Freedom (DoF) in the g008 group in AquariumStand.slvs but I don't think I do. Seems to be the middle box on the side farther along the x-axis in that sketch group. I've tried many changes and redrawing the offending area without deleting the group. Is this a known issue or am I just missing the unconstrained DoF? If it is indeed a bug and you want more data I can supply a file from before it was broken too.