MU sometimes receives incorrect empty result from CU about ao HOT 6 CLOSED

Steps to see the issue. The issue seems to happen ~90% of the time. Few times I saw it work as expected:

1. Create process A
2. Add handler to process A

Handlers.add(
        "test-action",
        Handlers.utils.hasMatchingTag("Action", "Test-Action"),
        function (m)
            ao.send({Target = m.From, Data= "This message will never be created"})
        end
)

3. Create process B
4. Add handler to process B

Handlers.add(
        "test-action",
        Handlers.utils.hasMatchingTag("Action", "Test-Action"),
        function (m)
            ao.assign({Processes = { PROCESS_A_PID }, Message = m.Id})
        end
)

5. From process B enter

Send({Target = ao.id, Action = "Test-Action"})

Result:
Message created in the handler in the process A is generated in the outbox, but it never gets send to Arweave.
Issue seems to be that MU gets empty response when it checks that result.

EDIT: Result isn't empty when checking manually. Link from the screenshot: https://cu.ao-testnet.xyz/result/ssswMSaMAnBTPePuEZMMVVHhWfPbAu8NW1MIzDaat2E?process-id=8fqIU38gHr06EqURPj80VNbIn-W436oQZa2UZ5WE7-0&no-busy=1
EDIT2: Above link isn't showing new message in the results anymore. See few comments down for new example + screenshots.

from ao.

from ao.

This is different.
At the time of the original issue, there was some confusion about what's happening. And it turned out that the assigning part actually seems to work fine, but the message resulting from that never reached Arweave.

This may not actually be related to assigning, but those steps just seems to be repro-able

In the repro steps, at the end, the MU gets empty result from the CU result link. But if the link is checked now, it can be seen that there is a outputted message there, but this one never reached Arweave (See screenshot of MU)
Forgot to mention that, and link to the result got hidden with the screenshot.

from ao.

Also more context: We're sending the message to B, not A.

What we're trying to show here is something like this flow:
Message 1 to Process B > Assigns Message 1 to Process A > Process A sends reply to Process B (msg.From from Message 1)

from ao.

For some reason this link in the second message returns now an empty result. It definitively had a new message there before. (EDIT: And still has when checking on local CU)
https://cu.ao-testnet.xyz/result/ssswMSaMAnBTPePuEZMMVVHhWfPbAu8NW1MIzDaat2E?process-id=8fqIU38gHr06EqURPj80VNbIn-W436oQZa2UZ5WE7-0&no-busy=1

Here is a new link+screenshots showing the issue. (Also a screenshot of what I see when checking CU manually, in case it changes again. )
https://cu.ao-testnet.xyz/result/rzu6lIyxSVIlL6zvUZZ7Wxj1kzjyZp9HfNuYhfWYA5c?process-id=tzMcL9smF0Z-HbzM9Fr8TfYsPx4wSUSiG676lViyORc&no-busy=1

Can see a new message in results, but at the time MU checked the same link it didn't see the message. And message didn't made it to Arweave.

from ao.

I'm going to close this and open a new issue now that we've isolated the root cause more.

from ao.