Re-entry of credentials required when file is accessed from FM Cloud

Product and version FileMaker 15.0.3.305

OS and version Windows 7 Professional SP1

Hardware Dell laptop, 8GB RAM, 64-bit OS

Description and how to replicate I'm opening a hosted file (B) from a local file (A) via script. The accounts and credentials that exist in A also exist in B. (I have also authorized A to access B, but from my testing I think that is irrelevant to the problem.)

When I work strictly locally, if I log into A as a regular user (password required, read-only access) and run the script to open B, B opens read-only. If I log into A with full permissions and run the same script to open B, B opens with full permissions. In both cases, B opens without any re-entry of credentials, which is the desired behavior.

However, when I upload B to FM Cloud and modify the script to open the hosted version, the behavior is different, but only when I log into A as a regular user. In that case, when the script runs, the system requests the credentials for accessing B. That is a problem for the synchronization routine I want to set up.

Workaround I thought maybe I was doing something wrong and so posted to the Community discussions (Re-entry of credientials required when file with restricted access is hosted on cloud? ). However, I haven't heard anything about the problem itself, so it seems like this may be a bug and not user error. I tried using GoZync as a work-around (couldn't use MirrorSync because of the limitations it has with FM Cloud), but it has the same problem. From reading I've done today, I have found that FM Cloud differs from FM Server in some ways that could be correlated with this problem, but I have no way to test this.