Oh no, a wild modding bug!
In the above video, I am holding Right Click to use a leap skill as soon as I can. This skill is equal to that of Rune of the Dreadnought (leap_d207.dbr) in all ways except for having a lower cooldown (1.6s). However, as one can see, the player is stuck in place for some time after using the leap.
Further testing revealed, however, that the issue above only occurs when targeting the ground. When targeting enemies, leap can leap off its listed cooldown unrestricted.
For what it’s worth, no, this won’t happen in the base game - the cooldowns of the fastest leap runes are too long (3.5s) for this irregularity to occur.