So not all ASIO are the same. Combine that with the fact that RealBand is a bit finicky, this is a common issue. There was even a very recent discuss which may help you.

https://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=635707


BIAB – 2025, Reaper (current), i7-12700F Processor, 32GB DDR4-3200MHz RAM, 1TB WD Black NVMe SSD, 2TB WDC Blue SSD, 1TB WD Blue, 2 TB SK NVMe, 6 TB External, Motu Audio Express 6x6