First this should only be possible if both chains are using the same address-pubkeyhash-version and address-checksum-value parameters so I'll assume that's the case. (It's generally recommended not to do this across chains, to prevent this kind of mistake.)
If so, your solution is to get the private key (dumpprivkey command) for the address on the node and chain that the address was created on. You can then import that private key (importprivkey) into a node on the other chain. This will make the issued asset units available.
This will only work if the private-key-version parameter is the same for both chains.