There’s a new strategy article on Sonic Hurricane explaining the concept of proximity blocking and providing a few example applications. Here’s the link along with a brief quote:
Manipulating Proximity Blocking on Sonic Hurricane
Dating all the way back to Street Fighter II, every attack has its own effective range which triggers proximity blocking. If the opponent holds Back while within that invisible range, they’ll stand still in defensive stance instead of walking backward.
Using this knowledge to your advantage is a key element of advanced footsies. The easiest offensive application is whiffing a jab while your opponent walks back and forth at mid-range. This will momentarily cause them to get stuck in place.