ORIGINAL: Marshall Ellis
This is definitely an issue with how I handle loaned corps.
I have changed this for 1.05 so that if you enter an area with loaned corps (Where the original owner is hostile to you) then the corps reverts to the original owner thus allowing combat. This has also been done for fleets (Only if you attempt an attack).
You could either wait until BETA 1.05 OR I could revert the corps back to Russian control? Your call...
To clarify, the original owner's DOW status should also be used if it's the borrower who is the phasing player, correct? Because otherwise, you run into scenarios where France loans his blockaded fleets to Spain, who merrily steers them past the British fleet (an obviously game-breaking abuse if the loaned fleets are allowed to pick up and drop off French troops while on loan...).
Edit: of course, if the UK fleet moved after the Spanish fleet, he might DOW for carrying French troops just as if the borrowed fleet were neutral. There would still be problems in land operations, however, and merely being able to escape the blockade might be useful.