Dear Silvia,
Sorry, but I still do not have a good grasp of what you problem is. If possible, it would help if you could screenshot the situation from the log you have an issue with (show which steps fail ... or pause ... or ...)
You say that you have to force the flow to continue ... I can't really imagine.
I have never seen a flows just stop, it will continue executing until the last action in the flow (unless it terminates with an error before this or you use a 'terminate' action).
Happy flowing,
Koen