The ‘Arrange breedings for the stud page’ for Sionnach does not show me the usual list of mates booked to be bred, instead there’s just a sentence at the top op the page which says ‘Sionnach is not a broodmare!’ (which did make me chuckle!).
From my stable page, I clicked on Sionnach’s name in the ‘Sionnach has been bred to 1 mare notification’ which took me to his page as normal. Click on ‘Arrange breedings for this stud”. The page then loaded with the message mentioned above.
Additional information
I’ve checked my other three studs and have the same error message when I click on the ‘Arrange breeding’ option only with that stallion’s name instead of Sionnach.