Hi Andrew
Have not run into this issue as of yet, and we have had version 24.1 installed for some time ( today, we just upgraded to 25.1, the latest version).
Forms are hard to debug without the solution and a bit of context, especially with the plugin in case that flow is repeated because it's in a loop. However with a button, I would look at rules that execute a web service (aka script) and also ensure the logic for the plugin doesn't also do the post.
For example, I have one solution that allows you to set a flag to do a background post for some scripts later in the process. If there are errors, it routes it back to a person to fix the data and then finally post in the foreground. You have to ensure both don't happen - foreground and background - especially important with repeating, but you are sharing that's not the case.
Also, please check the script in case there is a loop or IFs that may do something unexpected - although this suggestion is a long shot :)
I suggest opening a support ticket. They will likely need solution logs with tracing level set to debug. It's also helpful to know if it's just this one solution or all solutions and if there's a flow through the process that causes it.
You can also attach the solution here and I can take a look, but support will be your best route for a resolution, as they can engage others like engineers, as needed.
Best Regards,
Sigrid
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Sigrid Kok
*Precisely Software Inc.
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