one-zone burner at constant density

I was trying to use the one-zone burner at constant density from $MESA_DIR/net/test , with an initial composition of pure helium, logT = 9 and logRho = 5, and I noticed that the temperature didn't evolve much (changed only by 1d-8) when I used a net like mesa_125.net . The simplest net that shows this problem is one with only he4 and c12. However, the temperature does evolve (logT changes by 0.2ish) if I use approx21.net, or if I use other nets with use_3a_fl87 = .true. (e.g., by adding the line `g% use_3a_fl87 = .true.` near line 236 in `$MESA_DIR/net/test/mod_one_zone_burn.f90`).

I dug deeper with the he4+c12-only net. I added some print statements and found that `eps_nuc` returned by `eval_net` (called by `burner_derivs` in `$MESA_DIR/net/private/net_burn_const_density.f90`) is zero , while `dxdt(:)` gives the right rates. I should also note that `eval_net` is also called by `burner_jakob` but returns the right `eps_nuc`.

I used the same conditions (pure He, logT=9, logRho=5 and he4+c12-only net) with sample_net (which also lives in `$MESA_DIR/net/test`) and got the right `eps_nuc`, so I think this behavior seems to only affect the one-zone burner. I'm using 24.08.1, so reverse 3a and detailed balance with >2 reactants are also not the problem.

I'm attaching my inlist and net here.
[he4_and_c12.net.txt](https://github.com/user-attachments/files/17139133/he4_and_c12.net.txt)
[inlist_one_zone_burn_pureHe.txt](https://github.com/user-attachments/files/17139134/inlist_one_zone_burn_pureHe.txt)

Any pointers/suggestions are greatly appreciated!

**Version**
- MESA r24.08.1
- MESA SDK VERSION: aarch64-macos-23.10.1
- OS: MacOS Ventura 13.1