Seeing precisely the same issue on Win 10 Pro (21H2) Build:19044.2006 Reaper 5.99 (x64) Intel Core i9-10900K CPU @ 3.70GHz 32 GB ram
Saving my current bass preset, selecting any other Modo bass instrument from the instrument dropdown, and then returning to my original bass preset can restore the missing note range playback on my system.
Please report your issues to IK Support for direct technical support or reply to the support emails if they have not yet resolved your issue. Thank you.
IK Multimedia. Musicians First. YouTube - Facebook - Twitter Need help? Our support team will be happy to help and can be reached at this link. From the rules: Moderator decisions are not a matter for forum discussion and are final.