1. In General Ledger, Journal Entries, select Posted and filter for the date the check was entered. If there is a posted batch for this transaction, the check was processed.
2. In Accounts Payable, Open, select Vendors and open the vendor record.
3. Select the Activity Detail tab and note the stage of the manual check. If the check was processed it will be in the paid stage (typically stage 60).
4. Check the paid folder to see if the obligation is listed.
5. Select File, Print Manager to see if a OTMREG.L## report was created. This is the Manual Check Register and if the obligation is listed, the check was processed.

Following is an explanation of how the manual check folder works:

If multiple manual checks are entered by one user, they will all be posted together, even though just one row is highlighted and Post selected.  Anything in this folder, by user, will post at the same time. There may be more than one trace report, if some checks were for existing obligations and others were for new obligations.
Obligations entered as New Manual checks by another user will not post until the 2nd user logs in to post their own entries.

In other words, everything an individual user sees will post, even if they only highlight 1 row.

For new obligations, there will be a trace report with a purchase journal and a cash disbursements journal on it.
For existing obligations that are already at an invoice stage, there will be a trace report with a cash disbursements journal on it. 
For existing obligations that are at a PO stage, there will be a trace report with Encumbrances (assuming P.O.s are posted to the GL), a purchase journal and a cash disbursements journal.