I'm sorry for this late reply.
Finally I got my hands on the strip board and spent some time to built it.
As you may note there are some modifications in the adapter plate. I removed the SMD resistors and placed 10K resistors between the adapter plate and the strip board.
At this point I think the whole process is a little bit reliable.
However, I think maybe my problem is now related with the flash cycle count. I read here about it.
In the next weekend I'm going to replace my first one ESP12F to another unused.
I'll give replies about it.
Thank you in advance.
Regards,
LA