Assignments in Send() only work sometimes

[keikari]

Steps to see the issue:

1. Create two processes in Aos
2. In process A do Send({Target = ao.id, Data="Test message", Assignments={ "processB-pid" }})
3. The message sometimes doesn't get assigned to processB (Repeat 2 if needed)

Example:
This tx 67HuSGqiIx7hW5-0FGS0C1hTNUdmP-2CFOGXb5CqDK0
resulted to a new message with a tag: {name: "Assignments", value: "SqFaEjsVvlDV8xynJioE_Rerlfi9kflAux-MN_s2mt0"}
Result: https://cu.ao-testnet.xyz/result/67HuSGqiIx7hW5-0FGS0C1hTNUdmP-2CFOGXb5CqDK0?process-id=pI2ZDHs5111yXL0iZWIAijuhN25LHvRxRhmjfnZrGKw
But the new message dlGkShLq9zmH8G-Go4-lrG2Fx0w5flflW4ZAfXaL5iw has only been assigned to the target process(A).

Note: The issue seems to only happen with default MU https://mu.ao-testnet.xyz, when using locally setup MU all messages seem to get assigned as expected.