Employer Missed First Elective Deferral For 401k

I became eligible for 401k participation as of January 1st, 2025 at my current job. I have previously clearly communicated my desired contribution percentage and that they be made pretax, and completed account set up and investment selections on our record keeper’s website. Because of a mess up by HR last year regarding a different benefit, in August I made clear how important I viewed it that my 401k contributions were correctly made “from first pay period of eligibility.”

On my first pay check of 2025, no 401k elective deferrals were made. HR made an excuse and apologized but didn’t clearly answer my question about how my elected deferral and employer match from last pay period would be resolved.

I’ve been reading a little about ERISA- would the employer be able to basically just double my deduction and employer match next period as a catch up, or would they actually be required to make a corrective contribution NQEC on my behalf for last pay period? Thanks!

Leaving off my state location since ERISA is federal law but let me know if state might be relevant.