Carryover Expiration expiring incorrectly.

We're experiencing an issue with one worker's carryover expiration. The plan is set so that the carryover balance is added on January 1st and expires on April 1st. This worker had a carryover balance of four days, which they used between January 1st and March 31st. Ideally, the carryover expiration should be zero days, but it's showing as 1.5 days. (See attached screenshot for reference.)

This issue has only appeared for one employee so far.

What could be causing this issue to occur only for this specific employee?

Currently we are using 23D.

Any advice or insights would be greatly appreciated.