the default is to show full feed… please check your settings on forum – options – global settings… in the rss section and make sure you dont have an excerpt count specified..

The setting is correct.   Yet it still only is displaying excerpts.  Is there anything else that controls whether it generates full posts or excerpts?  The RSS feed prior to the upgrade to 5.0 did contain full posts.

It appears to be working just fine on our site here. Are you 100% sure this is not a product of your RSS reader? After all many, maybe even most, do enforce their own limits… at least that is my experience.