Units and Annotative Blocks

98% of my work is imperial, inches.

I think that I should be able to insert an Annotative Block, drawn in Inches, into a metric drawing and it should scale accordingly. That doesn't seem to work.

I have a Grid bubble Block, INSUNITS 1, with a circle that is 7/16" dia. and I insert it into a metric drawing, INSUNITS 4, INSUNITSDEFTARGET 4, INSUNITSDEFSOURCE 4, scale 1:50, and the circle measures 21.875 (50 x 7/16). But I need it to scale 25 or 25.4 to millimetres. Shouldn't it do it automatically since Acad2008?

There's got to be a setting that's messing me up.

Here's another strange thing:

I am copying / pasting some of the architect's backgrounds onto my drawing. Architect has some blocks that say in the Properties "Block Unit = Inches" and "Unit Factor = 25". If I copy those into my drawing they come up as "Block Unit = Unitless" and "unit Factor = 1".

If I copy just his 2d lines that represent walls, it comes in fine. If I copy and paste walls, hatch patterns and blocks it all comes in 1/25 scale! Including the 2d lines.

Both drawings Units are set to millimetres.

I've decided it's an Autocad error. I created 3 new blocks of aluminum channels of various sizes. They all have the same units and UNIT variables. I inserted all three into one drawing and one of the three came in 1/25.4 smaller than the other two.

I also feel mental illness coming on because I seem to be talking to myself on this thread. See you soon, good-looking!