STEM OPT application affected by H-1B Cap-Gap

Hi,
My H-1B case was filed and is currently awaiting decision. Since H1B was filed active post completion date got automatically extended to April 1st 2026 in my Sevis portal.
I’m now preparing to apply for my STEM OPT and requested an updated I-20 from my university. However, my DSO informed me that they’re unable to generate an I-20 with the correct 24-month STEM OPT dates (July 9, 2025 – July 8, 2027) due to a H1B cap-gap on my SEVIS record. Instead, they provided a letter explaining the issue and advised me to include it with my STEM OPT application to USCIS. Do you have any insights on how to proceed?