Yes, the OM System OM-5 is compatible with the SanDisk Extreme PRO SD UHS-II V90 128GB.
SanDisk Extreme PRO SD UHS-II V90 128GB is V90 class. Meets the floor for: 4K30 (30 MB/s floor). (Peak write 304 MB/s is not evidence of sustained performance; the V90 class rating above decides this.) OM System OM-5's own instruction manual requires an SD card supporting SD Speed Class 10 or higher, and a UHS Speed Class of 3 or better, for 4K/C4K or ALL-Intra recording -- V90 clears that floor with wide margin.
“When recording movies, use an SD card that supports an SD speed class of 10 or higher. A UHS‑II or UHS‑I card with a UHS speed class of 3 or better is required when:”
Last verified:
Compatibility inferred from spec rule (citations above are manufacturer-verified)