Ah, okay, I did not try it that way. Thanks for explaining.
When setting mass to 1 solar mass I see a black star, that's certainly a bug. I'll make a note of this on our bug list, but I'm not sure it will be fixed in time for our next release. Hopefully soon after.
In the meantime, you can increase the mass (instead of setting it to 1 sun) to keep it from breaking.
Thanks for reporting the issue!