Dormammu Soul Bond not charging

Recently I have discovered that Dormammu's soul bond sometimes don't charge. It seems that it works fine at the beginning, but every time after I do a power lock with sp2, I can still drain power with the normal 5-hit combo but my soul bond will not increase. After the power lock expires, sometimes it works and sometimes it doesn't.
1
Comments
The bolded part is what we're talking about. You've got an accurate description of how he's supposed to work. But sometimes, even with all conditions satisfied, the Soul Bond won't charge. I might start recording a few Dormammu fights to see if I can catch this on video. To date, I don't know what triggers it.