Backup from 13.00 local time today, you posted at 18.30 local time. Game date is 1960-02-26.
Went to Staff page, Quick management tool: Selected "All groups" to staff group selector, then selected "Raise salaries by" to action and selected 1%. Pressed 'set', and save. Worked normally. Though the 1% difference was so small that added with the roundings, it really did not affect that many groups.
(salaries are rounded to nearest $10 and 1% more to $400 is only $4 so it does not make any changes)
=> Can't see anything wrong ..