CONNECT engine JDBC remote index prevents UPDATE

If I declare a CONNECT table (test case is using MS SQL Server) I can easily issue simple UPDATE statements like:

UPDATE MyConnectTable SET name = 'bob' WHERE id = 23

The above works great. However, if I add a remote index to the table as follows (or during the CREATE TABLE statement) the UPDATE will fail:

ALTER TABLE MyConnectTable ADD INDEX (id)

For some reason it appears that CONNECT won't let me issue an UPDATE if I declare the primary key column of the remote table as indexed.