This is the same guy we looked at in February! The one with the buck. He finally recovered from the bone bruise injury then there was the COVID delay when their barn wasn’t allowing visitors for awhile and now here we are 
And it seems like the bucks may indeed have been a saddle fit issue. When we tried him again post-recovery our trainer pointed out that husband’s saddle tree was too narrow. He used my saddle and no issues–even over some novice-level solid jumps. We’re still going to have the vet make sure there wasn’t something physical we missed, but it’s a positive sign.
Apparently he looked better today so maybe it was just an odd tweak. When we brought him in, he did have a big rock wedged in the favoring foot and his feet are pretty flat (first thing vet said is he needs front shoes–he was trimmed in the last week so farrier may have taken a bit too much off). In any case, hoping for better luck next week.