Specifically, here (assuming you installed to the default directory):

32-bit: C:\Program Files\Stardock\ObjectDock Plus\Bundled Images
64-bit: C:\Program Files (x86)\Stardock\ObjectDock Plus\Bundled Images 

I guess the icon browser is just quirky (being polite).
The first PNG I copied to the Bundled Images directory promptly showed up. Yea!
The second one, did not. Boo.
I stopped and restarted ObjectDock, no change.
It's just weird, OD sees some of the custom icons I have, just not all. No rhyme or reason of which ones.
Oh, and I am running the free versions of CursorFX and LoginStudio.
FWIW, I installed to a non-standard path "C:\Utils\Skins\ObjectDock". Which means install images are at "C:\Utils\Skins\ObjectDock\Bundled Images\Applicaitons". And my user icons dir is at "C:\Work\Data\Pictures\Icons\ObjectDock Icons\Apps" To me the paths don't look too long or have too many spaces, etc. And I am W7x64 wUAC off.

Thx
S

Huh weird. I posted a thanks the other day, it was late, but posted. And now I don't see it at all. OK, I'll try again then.

Thank you Zubaz, making the icons square seems to be the fix for me!
I knocked out a couple of trial icons in IrfanView and they worked.

Now I have another quick question.

IrfanView is normally my go-to, but it is kicking my butt here. I keep losing the transparency of the icon background, it goes black.
Is there an easier tool/method for just reformatting? (I'm not an artist so I won't be doing much creation, if any.)

Thanks again!

S