This behaviour would actually explain whatI was already saying...it seems your history settings are not really okay for your use case.the history seems to work bader the longer PF is running and working a bit better after restarting
When you (re)start ProppFrexx the Media and Script History might not be reloaded (depending on your settings, e.g. if you didn't activate the 'Keep Song History persistant').
In that case your 'News' tracks might be scheduled due to NOT matching any history.
But after some playouts, your history might 'grow' and more and more tracks might violate your Song History and are as such not scheduled anymore.
Please try the following settings:
a) News Media Library (Default EntryType='News'):
Song History: 2 or 3 (instead of -1)
b) News Script(s):
Song History: 0 (disabled)
c) Global Song History: