File got wiped out or deleted - was it caused by simultaneous read/write?

When there is a text file in the file manager space, is it possible that it can be wiped out by being written to at the exact moment it's being opened for reading? I have the following legacy RM rule which gathers specific reports during the day (usually no more than 100 lines) and then deletes and remakes each day at 10pm

This has been working as expected for many months.

Yesterday I checked the log at just after 7am and it had the expected 3 lines. I checked again a little later and it only had lines going back to just after I checked the time before. The 3 lines I had seen had disappeared from the file. I checked thoroughly and the ClearAlertsLog virtual switch had not been operated and there was nothing logged that could have caused it.