Well, parts have well defined working limits and requirements under which manufacturer declares them to work consistently (or should work) regarding various physical conditions that part might be exposed to.

I believe that you step out of those limits with EMI from RLY, so, basically, you can't expect that each and every of your parts act consistently since you put them in 'gray' zone. They might work, but, than again, they might not which is precisely the situation you have.

Bottom line - if you use your mCs outside of specified requirements you can't rely on them working as intended.

Best luck,
CN