First time using 0.4.1, I sent a tug up with a single kerbal in it, to deorbit some debris. I got close to some, went on EVA, grabbed the attachment point, and suddenly my jetpack wouldn't work. I'd get the animation but it didn't seem to actually affect where my Kerbal would go. He slowly drifted away from both ships.

I went back to spaceport and then back to the ship (which usually fixes oddities with KAS and EVAs) to no avail. I unloaded and reloaded the game, however, and had control over my Kerbal with no further issues. I was able to grab another connector, attach it, attach the winch, and all that.

Normally fixed in 0.4.3