[Coltnut]

Ive had two guns in past that did the same.I chucked it to tolerance stacking when link straightens out and the bottom inside of frame while top lugs of barrel hang up on top.If you get it just right it all binds up.
When installing slide assembly the link is dragging with bottom of link trailing so you wont see the binding.When removing the slide -due to the link being slightly forward it will straighten and if not enough clearance on bottom of link it will bind.
A couple of non Colt 1911's i have actually have a small slot machined under barrel link inside the frame for link clearance.
I never did anything to repair that issue,just shook the gun after removing the slide stop to get link to shift to a different position then removed slide.
Hope this makes sense.

 

[Coltnut]

rather than machining the frame, wouldn't it have been easier to
file a little off the bottom of the link ?

That would work,the guns i had with the machined area under link came like that from factory.
But some dykem or a sharpie to blacken area in frame under link to find area where its hanging up would help to relieve
the link from locking up.

 

[Coltnut]

Borrowed a picture from a different post on the site.
If you look at these frames you'll notice the machine area under the barrel link to prevent hanging up.
That would be the area to clearance slightly.Or to look for a mark after dykem or black sharpie was used.