In AX 2012 R2, before Cu6, the following issue occurs:
project timesheets vouchers are not ok for intercompany postings. Trying to post an intercompany timesheet for projects, the system uses a wrong posting date for part of the voucher. Moreover, as a consequence, the entire posted voucher is visible only in the G/L and not in the Project inquires (refer to the attached document for details).
There is not a specific KB solving this issue, however it does not occur in AX 2012 Cu6. The issue has been indirectly solved by other KB fixes: this can happen when there are a lot of fixes that insists on the same area/module .
In Cu6 there are many fixes related to Project module and also specifically to the Timesheets management. You can check and download them on the Partner/Customer source.