Here is an article in English:
https://nltimes.nl/2025/10/29/ns-hit-microsoft-cloud-outage-...
It should be noted that the article isn't complete: while the travel planner and ticket machines were the first to fail, trains were cancelled soon after; it took a few hours before everything restarted.
Based on what the conductors said, I would speculate that the train drivers digital schedule was not operative, so they didn't know where to go next.