In simple words ALG do a dynamic Port opening based on the application type. By default MSRPC alg is enabled on Junos devices and the error message you seeing could be some software issue needs investigation. I would recommend you opening a JTAC ticket to get this investigated further. For a quick fix you may try disabling MSRPC alg and open any/any policy in both direction between server and client .
disable MSRPC ALG:
root# set security alg msrpc disable
root# commit