I’m also in trouble with this glitch. I had a carcass Mrs. Hobbs, was going to request in future & now I can’t receive a follow up request from the museum.
The glitch has been documented here:
http://www.powerpyx.com/red-dead-redemption-2-all-hunting-request-locations/
It would seem my options are to either continue & hope Rockstar fix it.... or ..... I select a save that will reverse my progress by 45%.
This glitch has stopped me from playing as I am trying to gauge my options before I continue.
Any workarounds would be very much appreciated.