Hi @lah7,
"Welcome" won't load available software lists saying that there is no software available in any particular section!. 
The software lists are up-to-date despite the message bottom left in the pic!.
Makes sense, Welcome and the Software Boutique hasn’t yet been updated for 17.04, so none of the software listings “know” they work under zesty.
Good timing too, that’s what next week is assigned to do, plus a lot of other internal changes. 
In the meantime, you can workaround by typing:
ubuntu-mate-welcome --force-codename=xenial
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Thanks Luke, that has solved the problem!. 