F4211 Last status clearing

Hello

Do you know what may cause a last status to clear in F4211. We have had this happen a couple times where they had a status at one time but for some reason we go back and it's gone. For example we had an order at 900 last status and 545 next status and went back in a day or two later and was blank for last status and 545 next status.

This does not happen all the time and I cannot duplicate it but I didn't know if this is a known issue or you could point me in the right direction.