The next gen rule engine has had a lot of updates since 2.3. The issue reported in the OP may no longer be an issue on a newer build. It seems to not effect everyone all the time. Here is an open ESH issue for what is reported in the OP…
https://github.com/eclipse/smarthome/issues/4324#issuecomment-427836598
Also, this would cause a problem with your use of the JSONPATH transform…
I suggest you setup JSR223-Jython, which includes a startup delay script to prevent the loading of rules until everything has been loaded. The links I provided go to a branch that has not been released yet, but I hope to have the PR merged this weekend.