[0.15.9] missing materials count is fluctuating

[Cutemine]

Hi!
I just noticed the alert for missing materials is fluctuating rapidly. At first I was pleased as I was guessing my robots must be putting items down quickly, but the displayed number actually increased and decreased more or less randomly. This was not caused by my personal roboport as I was standing in a completely different part of the map. Also, the total count of 601 objects stayed constant:

I attached the savefile below.

[Rseding91]

That's working as intended. The display shows all active alerts counts. Alerts last 600 game ticks and the game checks for new alerts once per tick so it cycles through all of the things on the map needing to be built.

[Cutemine]

Does this mean no more than 600 missing items can be shown at once? Because I could swear I've seen bigger numbers.