Perhaps you ought to describe what it's doing (wrong) for you in some detail.
I'm able to use Image - Adjust - Threshold, recorded in an action, no problem. Unfortunately I have only access to 13.0.1 because I have a perpetual license. Is it something new you've seen happen only in recent updates?
I'm having an issue too in 13.0.4 with Threshold as an action.
If I add a Threshold Adjustment Layer manually in the Layers Tab it will pop up in the Properties Tab and will work as expected.
If I add a Threshold Adjustment Layer in the Action Tab as a new action and toggle dialog on, the action will run, the dialog will pop up in a separate box (as opposed to the Properties Tab), but if you drag the slider to the left, add a sample color point (shift click for #1) and move the slider right (with the intention of adding another sample point #2, the original point #1 will often disappear. In previous versions, the #1 point would persist while dragging the slider.