@CircusPeanut I had the issue before updating to v11.1 so I don't think it is caused by v11.1
There is more than one reason why transactions might not be accepted by core.
To be certain that you are encountering the same issue that I'm fixing right now, you have to find this string in bitcoin/debug.log
ERROR: AcceptToMemoryPool : nonstandard transaction: scriptpubkey
For instance if you attempt a double spend, everything acts the same failing to use "lowS", but you find this in bitcoin/debug.log:
ERROR: AcceptToMemoryPool : inputs already spent
Another one that I think is probably what you encountered is:
ERROR: AcceptToMemoryPool : free transaction rejected by rate limiter
0.93.2 has a bug in it that provides a very old age for inputs when it tries to verify the fee you specified. So instead of telling you that the fee paid is not enough for a transaction with many inputs, it thinks that since all of the inputs very old, it should be free and doesn't warn you need a bigger fee. Then transaction gets rejected by core, and you don't know why unless you look at the log.
Goatpig... please make sure your fix for that gets into this bug fix release.