Adding a stroke to a frame layer (CC 2019)

Adobe Frame layers are a strange  Photoshop layer. Adobe State that Frames are like a mask and they are depicted like a backwards layer where the Frame mask is on the Left and the Layer Content on the Right.  A Frame mask  does not mask like a normal layer mask or a vector layer mask and you can not add a normal or vector mask to a Frame layer.  If you add layers style the way the effects are generated may not be what you expect.  Though you can add layer styles they most likely will not be the effects you may be expecting.

Also if the image you place in has transparent boarders they will most likely be trimmed off by Photoshop's Place feature when Photoshop renders pixels for the smart object layers content. So the Image may not be position like you expect it to be.  Copy Paste has the same Trim boarders problem.  The way I get around this is I put a 1% opacity pixel in the top left and bottom right corners of the Image canvas to eliminate transparent borders with two pixel the human eye I will not see.

The Transparent Border thing.  Here I use two different JJMack png files with transparent boarders one with the 1% opaque corner pixels the other one did not the PNG files are the same size and resolution, Frames created two differen size smart object layers