https://circuitverse.org/users/49622/projects/subcircuit-problem

I created a minimum circuit that demonstrates a problem I saw in a larger circuit. In this circuit, there's an input with a tristate gate attached to a common bus. Also on the bus is a D flip flop, with it's input from the bus, and it's output sent to a tristate gate which outputs to the bus. That's the upper circuit on the Main tab and that all works fine.

When I put the D flip flop into it's own subcircuit, I get 'simulation stack exceeded' when I change the input and try to latch that into the flip flop. That's the bottom circuit. So it's the exact same components, but just one of them is in a subcircuit.

Has anyone seen this behavior? Maybe I'm doing something wrong?

Thanks