But now there is another error:
A failure occurred because the name of the server arsserver is not in the list of valid mid tier servers
Can you please check if this form is present in Dev Studio.
Once you confirm, please post the screen shot of how you are searching.
The permission does not seem to be an issue as the form has public permission.
If this does not help – in few cases – I have seen – stop mid tier, clear cache folder (take back up) and restart.
Not sure if this is feasible in your case though since it may be prod env.