We've discovered a possible cause to this behavior. Export As maintains a preference file to remember your settings between sessions. If this file becomes damaged or corrupted, it will cause the dialog to look like this. Please go to the following folder, delete the prefs.txt file there, and relaunch Photoshop:
- Win: C:\Users\[USERNAME]\AppData\Roaming\Adobe\UXP\PluginsStorage\PHSP\23\Internal\com.adobe.photoshop.exportAs\PluginData
- Mac: /Users/[USERNAME]/Library/Application Support/Adobe/UXP/Pl
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