Hello, I'm sorry you're having this issue! I'll take a look and see if I can find incompatibilities and fix them as soon as I can, in the meantime any additional information you can give will surely be helpful. Thank you for reporting this issue!
Viewing post in Ritter Ultimate Event Spawner (RPG Maker MZ) comments
Okay I think the issue here is actually unrelated to Visustella Core MZ. When you placed the updated version of the spawner into the demo did you reconfigure the plugin parameters?
In the spawner update to 1.5 there is a new Developer Mode which is still unfinished but this Developer Mode seems to be clashing with my own demo file. So to get around this issue just disable it.
Try this:
Open plugin manager and open Ritter_EventSpawner.
Set Developer Mode Parameter to False.
Set the Developer Mode Alert Settings to False.
Playtest again and see if it works.
Be sure to let me know if this doesn't resolve your problem!