base64 decoding fails when assigning bash variable?

Question

I have failed to understand the following behaviour. First encoding that seems ok to me:

$ echo -n "Cg==" | base64 -d | xxd
00000000: 0a
$ echo -n "Cgo=" | base64 -d | xxd
00000000: 0a0a

When I assign the decoding to a variable I lose LF in the process.

$ VAR=$(echo -n "Cg==" | base64 -d)
$ echo -n $VAR | xxd
$ VAR=$(echo -n "Cgo=" | base64 -d)
$ echo -n $VAR | xxd
$

That is I do not get anything back other then null ("") instead of 0a and 0a0a respectively. What am I missing? Mistake in the example? Is this expected behaviour?