I think the whole data streaming error thingy occurs whenever UO has a new patch and you have to wait for UO Assist to update on their end?..
but what these fine folks are talking about is that in the meantime, in order to get your UO Assist macros to work you need point assist in the right direction.
To do that, find your UOAssist folder - open the folder UOA-Settings - open the account folder you want to fix - now open the shard folder - locate the character you want and make a copy of that folder - now go back to the shard folder and paste your character folder in there - click on any document and highlight a letter or w/e and copy that so that you clear up the huge file you now have in memory (i always do this lol, but not necessary ;p)
And repeat for every character, until UOAssist updates.