Business case hours jumping to Millions- is this a bug?

[SaraTo1]

We were reviewing our project business cases this week and noticed that millions of hours were added to random job roles in a handful of projects. This does not seem like a user error since I would assume they would notice on saving their business case edits...has anyone else recently seen a huge jump in business case/budgeted hours? Do we know if this is a bug of some kind? Or should I fear the worst and assume someone did indeed go from 600 hours to 6 million....

[JaneSt1]

Check task duration types...that sounds like an issue where some were changed to Effort Driven or Calculated Work.