as Rohit mentioned
can you please check if the work items exists in the ECC back end inbox
if yes, can you please click on the work item & see if you are getting the issue ---- also click on refresh & see if they still exist in the back end
please can you check the SM59 connection for portal- check if it is throwing any error
check for authorization as well - i do not think so, but just to role it out
do you have a inbox refresh button in ESS? if yes try it then see what happens?
if those workflow are not relevant & if you do not want then you can delete them from the back end? but if it is for everyone then it is not useful