50-200 AF Question

I recently purchased a new 50-200mm SWD and EC-14, and am curious about whether the AF (PDAF) behavior I'm experiencing is normal for the lens.

I've only had it for a few days, but have noticed that occasionally, when attempting to AF on something that is considerable farther away than the focus distance for the last shot, the lens does nothing at all when I half-press.

Today, trying to get a better handle on when this happens, I first focused on a point about 2 meters away. Then, trying to focus on an object about 10 meters distant, it would do one of two things:

Occasionally it would not even attempt to focus.

Most often it would attempt to focus and then stop before achieving focus, though there would be an AF confirmation beep. Absolutely nothing in the frame was anywhere close to being in focus or even recognizable. Just one big blur.

I repeated the sequence a number of times, and was never able to get the lens to focus on a more distant subject after focusing on a closer one.

This was outdoors on a cloudy, but not particularly dreary day, and there was more than adequate contrast (tree branches against a lighter background, for example) to work with. I didn't think of trying the same test without the EC-14.

The lens has updated firmware; camera is E5 (no AF problem with other lenses). Using diamond AF pattern, S-AF

I'm always able to give the focus ring a quick turn toward a more distant focal plane and then I can AF normally, so it's not an insurmountable problem, though I'd prefer to exchange the lens if this is not normal

Any thoughts?

--
George