Ampersands break context substitutions when used in the URL

If a substitution (node:title for example) contains an ampersand and is used within the URL, it creates a malformed URL.

"A & R, Test Page" ends up looking like so:
A%20&amp%3B_R%2C_Test_Page

As you can see above, it oddly starts adding underscores instead of spaces (%20), but only after the ampersand. Any help would be greatly appreciated. Thanks in advance!