Firefox freezes whenever I try to browse and upload a file using the system finder

For example, attaching a file to an email will bring up the macOS file browser. After navigating to the desired file and then selecting/clicking the file icon, both Firefox and the macOS file browser will immediately freeze. Note, the freeze happens when I selecting/clicking the file icon in the system browser--before clicking the [open] button in the finder window. Interestingly, uploading a file via drag-and-drop (if supported by the website) works perfectly fine. - The rest of my system does not freeze. Other macOS finder windows continue to work fine. - This uploading issue is not found in other browsers or programs that use the same macOS file browser. - Only "workaround" is to force quit FF, restore the browser session, and then hope the website supports drag-and-drop uploads. Or use another browser to upload the file. ## What I have already done: - Already "refreshed" FF. - Already placed FF in safe mode. Any help would be appreciated!