Hello!
I did find a bug that would cause the substitution to go on forever unless reapplied. I just released a fix with version 1.0.1... I was able to reproduce this behavior, and based on my tests I'm pretty sure it is fixed. But please let me know if the issue persists!
And I should say... thank you for the detailed error report! It was such a specific scenario, and your description really helped me quickly identify the issue!