net.openstack.Core.Exceptions.Response.ItemNotFoundException

using vb.net 2017 (15.7.5 (current)) and openstack.net (tried both 1.7.6 and 1.7.7 (current)), I am getting the following exception:

net.openstack.Core.Exceptions.Response.ItemNotFoundException

I tried putting the offending code in a try catch block using both

catch ex as exception

and

catch ex as net.openstack.Core.Exceptions.Response.ItemNotFoundException

and for each in debug mode the catch works fine and the code works as expected.

However, in each in release mode I get the following:

net.openstack.Core.Exceptions.Response.ItemNotFoundException
HResult=0x80131500 Message=The item was not found or does not exist. Source=openstacknet StackTrace: blah, blah, blah ..

any ideas for a workaround / fix (other than on error goto because there is already a higher level try block in play).

Thanks in advance.