(minor?) BUG - If you set a display to [] and let the display show an item count, and then clear the display, and then try to make a blueprint including that display, the item whose count was was shown initially shows up as a parameter option in the blueprint creator, even though there's no trace of the item in the display in-game. Mousing over the parameter shows the display as the source of the parameterized item.

You have to delete a display and recreate from scratch to get rid of this issue. Doing ctrl+x / ctrl+c of the display does not clear the bug.

Huh, interesting bug. I’ll investigate at the same time as the other bug.

To clarify, are these the steps?

1. connect a display to a signal source (ie. constant combinator) and configure it with a message and a condition.

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1. disconnect the display

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1. making a blueprint and opening the parametrise menu will still show the conditions on the display message even though the display no longer has a signal connection

If so, I have been able to reproduce the issue, BUT, I believe that this is a base game issue or not a bug.
The display likely keeps these conditions set even if it is not shown in the GUI.
That is why it is only when you place a new display that it will remove these options from the parametrise blueprint, copy and cut will also copy the settings (as they are stored in the blueprint string).

If it's that the number doesn't get set to 0 on disconnect, unfortunately I cannot update the message as that message is not available on the API.

Almost - I don't disconnect the signal. I just change the text on the display (or delete it) so that there's no item count being listed. E.g. I set it to show on 'anything' and put the Icon as Parameter0 and no text. So the blueprint shouldnt have any items picked up as parameters from the display but it still contains whatever teh mod displayed previously.

While I was unable to recreate I can see there is a forum post with a bug that has been fixed in the experimental release 2.0.25.

https://forums.factorio.com/123007

Can you confirm if this is the behavior you are seeing.