Actually found a decent enough workaround for it. This is what's currently set (as it was prior):
Changing it to:
Fixes the issue, however, if you need to cancel your The Cube ability moving forward you'd need to press 2 again; previously, it used, Space, yet the ulti used 4 again to cancel, which I think may have been uniquely programmed for Viscous given the way his ability utilises space for movement purposes.