Base hours incorrectly adding to Pay Employee

We manually enter timesheets for our employees. I have one employee that has twice randomly also had a figure in their base hours on Pay Employee resulting in the employee being overpaid. I have searched other posts for solutions.

I am aware any changes in the wages tab of employees card can effect the standard pay but on this occasion no changes were made.

We use MYOB desktop version, don't believe the clearing the cache solution will work?.

I have read of solutions being to untick the base hourly box but I get an error message "All hourly employees must be linked to the Base Hourly wage category". I tried to remove the hours in fortnightly pay period but it also would not accept that. The only solution I have is to change the hours in fortnight to 0.1 so if this random error happens they will only be paid a minimal amount, not double. (Not sure if this will impact anything else).

I find this quite frustrating and don't understand why it is happening.