Okay, so I noticed this in training mode against Rose. After I did cl.lp, cl.hk, c.mk xx EX PC, I could not combo into Sweep (c.hk), no matter how hard I tried. Rose is one of the characters that Rolento is normally able to connect sweep after EX PC against, so I was a little frustrated because I didn’t understand why it wasn’t working. Later, practicing against a crouching C. Viper, I noticed the exact same issue - this time after CH cl.hp xx Instant Stinger, c.mk xx EX PC. This made me want to dig a little deeper, and here’s what I found:
Full EX PC is 7 hits, but when it’s used from max range, its first hit whiffs. This is why c.lk/c.lp cancelled into EX PC from max range won’t combo - because the first hit of EX PC is whiffing, and the hitstun from the light attack dies out before the second hit becomes active. In addition, it seems that the 6 hit EX PC juggles the opponents lower than they would be by the 7-hit version, making certain follow-ups (read: sweep) impossible.
Note: This doesn’t apply to all characters. Rose and C. Viper both can not be swept after 6 hit EX PC, but Balrog can. I haven’t gone through the rest of the cast yet.