I swore I'd never do hotfixes after Adventure Sonic's Milne Chronicles, yet here I am...
When playing as characters other than SMB2 Toad, you would previously be able to do a partial version of SMB2 Toad's crouch. This flew under the radar because I didn't bother testing what would happen if you added the addon and then just played as a different character. Neither did anyone else, apparently. Well, that should be fixed now!