https://community.filemaker.com/en/s/question/0D50H00006o2xNgSAI/testing-an-existing-and-quite-complex-application-on-filemaker-18-ive-run-into-something-i-cannot-explain-despite-setting-import-records-in-a-script-to-no-dialog-a-dialog-appears-forcing-me-to-select-the-source-which-is-defined-in-the-script
It has been reported to FileMaker dev team which has been able to reproduce.
Worked fine until v17. Issue appeared in v18