it seems you did not create the said accounts but used the default accounts and then continued using them they were not designed to.
the said billable time accounts would appear only when you create atleast one valid entry in the Billable Time
tab. I suspect that you initially tried creating an entry in the billable time tab which created the related billable time accounts. then you started using the accounts directly in your invoice and then later deleted any entry you initially made in Billable Time
tab. the Manager update forcefully removed the default accounts since there was no entry in Billable Time
tab which is the intended correct behavior of the program.
i suggest you to create a test entry in you Billable Time
tab and check if the account reappears with the correct balance.