Would DOR be backdated for ARNG officer takes promotion in USAR?

Good morning,

I've been a 2LT for 36 months because the state could not promote me. They forgot to submit the Fed Rec in 2017 and it just got approved last week. Now I am transferring into the USAR but HRC informed me that they could not backdate my 1LT DOR to my date of eligibility if I take the promotion in USAR instead of ARNG. If I have to wait for my1LT promotion in ARNG, it would take at least another year and I would be a 2LT for 4 years.

Can someone verify this?

I looked up AR-600-8 and I thought 1LT promotion is automatic across RC and NG and DOR credit should be rewarded at the date of eligibility. I graduated from ROTC .