Hello, sorry to hear your having this issue.
As I understand your issue, things outlined in your original post work on shore power, but not the genset.
Your latest post indicated you followed Focker’s advise without resolution.
If you are comfortable working with electricity, it sounds like it is time to get a meter out and do some basic checks.
Ausmeing genset starts and runs, is it outputting voltage? The ac would leave the genset, likely tie into a Junction box near by and proceed to the transfer switch.
In case your not familiar the transfer switch is the traffic cop that controls the path of the electric. Both the shore power cable and the genset output hook to it. It controls the path either allowing it to pass thru from shore or genset to your breaker panel to feed your ac circuits.
It also determines which source is dominate.
If it were me, I would recheck my genset to ensure all breakers or fuses are not blown for some reason.
Than validate genset output with a meter at the genset. Move down the line to the junction box, revalidate both legs, proceed to the transfer switch and repeat validation. Then confirm that the switch is actually functioning(changing paths).
My gut is telling me the following
1. You have no genset output due to a tripped breaker or a-blown internal fuse on an internal circuit at the genset itself.
2. You have a bad connection or connections at the junction box
3. You have a bad connection or connections at the transfer switch
4. You have a transfer switch that isn’t working to change the path to the breaker panel.
If you are not comfortable working with 120v electrical circuits, it would be best to not investigate this yourself and call in a pro.
Hope this helps!