I recently purchased some used LEO trade-in magazines for my new to me CPO P229.  The magazines are of the zipper backed variety.   They do not drop free like my new magazines.  No big issues since they will just be used as beater range magazines.  However I do not remember having this issue with my last P229 (it's been 5 or 6 years since I last onwed one).  Was any of the older zipper back magazines designed to be non drop free?
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Not to my knowledge, but I've only had dovetail, not zipperback. Can you tell where it's catching?

Have you tried cleaning them? From the picture, it looks like that magazine still has some of the packing grease on it. That stuff is sticky as hell and a pain to clean off.

Not sure if gun stores clean that stuff off before selling their guns or if SIG only applies it to certain guns and magazines being shipped to certain buyers. I have never had that stuff on guns or magazines I have bought through commercial means but guns and mags I have obtained through gov. work all came with that stuff on them. It needs to be cleaned off before use.

I believe it is dragging on this little bump on the top of the magazine.  The magazine in my first pic is factory new.  It is drop free.  The magazines I'm having issues with are used trade-ins like the one pictured below.  
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The first magazine is factory new.  The second magazine is a ban era, no issues.  The third magazine is the type that is not dropping free.  They'll drop slightly then atop.  A slight tug and they'll break loose and then drop freely. Attached File

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Well, clearly the surplus one has wear on the top front but I don't see bumps in the picture. You can mark them and see what areas rub off.

Before that, I'd try keeping the mag release pressed and see if the mag goes and and out smoothly. That will tell you if the mag catch is dragging it or if it's just the mag body in the well.  I mention it because I see a bit of a mark above the cutout for the mag catch in your pictures. With the E2 grips, there's no grip screws so they're not sitting too deep into the magwell.

I'm realize I'm not being terribly helpful, but without it in my hands it's hard to troubleshoot.

I tried to get a better picture of the bump on the top of the magazine.  It's definitely dragging on the bump.
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That is interesting. I have more than a few 229 mags and I do not recall ever having one with a bump there. It does look like it was designed that way. Are you able to contact the company you bought them from and see where they bought them surplus from?

Maybe email SIG and see if they have an answer for you? It is possible an agency asked for non drop free mags and this is what you now have. I am just guessing here.

To add- I have factory new SIG, unknown surplus, and new Mecgar mags. I have mags for 226s, 229s, and 228s none of them have that bump there.