[HR] Can't enter horse competitions - game says no horse available

Product: The Sims 4
Platform:PC
Which language are you playing the game in? English
How often does the bug occur? Every time (100%)
What is your current game version number? 1.99.264.1030
What expansions, game packs, and stuff packs do you have installed? A lot - all EPs but Get to Work and Highschool, all GPs but wedding stories and star wars, most stuff packs, a few kits
Steps: How can we find the bug ourselves? Not sure - it was working fine until it wasn't. It started happening after repairing my game
What happens when the bug occurs? I try to enter a horse competition and the game doesn't register any horses as being nearby even though there are two eligible horses and two eligible riders
What do you expect to see? For the game to let me pick a rider and a horse and enter the competition
Have you installed any customization with the game, e.g. Custom Content or Mods? Not now. I've removed them.
Did this issue appear after a specific patch or change you made to your system? Yes
Please describe the patch or change you made. I repaired the game to fix a different issue - original issue was fixed but now have this much bigger one

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I was having the issue described in this post:

https://answers.ea.com/t5/Game-and-Mod-CC-Issues/Cannot-hand-feed-horses-with-produce/m-p/12765642

The post suggested repairing the game to fix it, and I did, and it worked - as soon as I opened the game I tested the hand feeding, it worked, and then immediately tried to sign up for a competition and I got the message that appears in the attached screenshot.

I'd already entered (and won) competitions before. I removed my mods. I tried it on my home community board, I went to the equestrian center and tried it standing right next to the door, I made sure to have the horses stand as close as possible, I tried it while riding on the horse, I tried it with different sims, I tried resetting the horses and the sims, and nothing worked. I might start a new save and try it there to see if it's still broken. If not I might try repairing again but I'm reluctant.

EDIT: taking the horses on a community job seems to have fixed it, somehow?