I do basically the same tests as you. It does not matter if you generate OptF in isolation or not, but there are indeed some simple methods to find problems fast. For instance, before training a system, do a test run with the raw, unoptimized script.

In this test run you can examine the log and check the error messages. If something's wrong in the script, as here with the missing short trades, you can identify and fix the problem before training the script. In this case it's the wrong profit target. Training won't produce error messages, wrong trades are just not executed.