I am thinking there is no bug, but even your simple example shows a bad use of properties and adds a special feature.
So it's up to your data. Only in rough terms (if you have any questions, just ask specific points)
First: Why you set units in sample_circle.dwg to inch, if the drawing is in millimeters?
1. Big-Point one: Your Block named 'CIRCLE' is defined differently in the two files, which is really a bad practice.
If you bind-insert the xref, all named objects/styles which a allready exist in targetfile(sample_source.dwg)
will refere to this existing definitions. So your Xref-Circle-Insert
It is less dangerous to defined it as one circle and one square, because this difference see everyone,
but your difference is only the diameter ob the Circle inside the CIRCLE-Block, that isn't easy to recognize.
2. The second big-Point: I don't know why (It makes no sense in the example files, but certainly in your original files)
You XCLIPed the ExternalReference Object see green text in screenshot)
What happen by bind-insert:
Acad imports all objects to the main files (sample_circle.dwg) and all named styles and definitions
but only not allready exist in the target file!!
A Block named "CIRCLE" existing in target file, so the blockreference from the xref will now refer to the
Blockdefinition of sample_circle.dwg.
In Xref, the Circle of CIRCLE-Block is dim1,7291, the circle of CIRCLE-Block in sample_circle.dwg is dim43.9192.
Now, the displayed circle blows up 25.4, but you had scaled the Xref with 25.4, so the the content of your
data is scaled 25.4. Now the displayed circle is blown to dim1115.55
So: Your Circle from xref-blockreference is very very hugh.
Why you can not see them?
Because you XLIPed the Blockreference(earlier the ExternalReference)
At this time the Circle is OUTSIDE the clipping border of you XCLIP, that
why you can not see the BIG circle in the drawing after bind-insert.
(bind-bind works, because the named object get a copy of there external definition, unique Layers, Blocks and so on,
then on block is named CIRCLE and the block from the xref is Sample_Circle-Embed 1$0$CIRCLE,
2 Block, one with a small circle, one with a big circle.
Test this out:
bind-insert the Xref, CTRL+A, now you can see your clipping border, use the arrow grip to toggle the cut-side.
Use ZOOM Extents now.
Or use XCLIP, selec xref, option DELETE, you can bind-insert now and Zoom-extents.
Can you see what i try to explain you?