After the update from Views 7.x-3.0 to 7.x-3.1 a context display was no longer available in Panels.

Got the same issue, but not when upgrading Views, but Panels from 3.0-alpha-3 to 3.0
In my case the problem lies with the query build for retrieving the nodes from the db, the query is setting the wrong node type.

SELECT node.title AS node_title, node.nid AS nid, 'node' AS field_data_body_node_entity_type
FROM
node node
WHERE (( (node.status = '1') AND (node.nid IN (SELECT tn.nid AS nid
FROM
taxonomy_index tn
LEFT OUTER JOIN taxonomy_term_hierarchy th ON th.tid = tn.tid
LEFT OUTER JOIN taxonomy_term_hierarchy th1 ON th.parent = th1.tid
LEFT OUTER JOIN taxonomy_term_hierarchy th2 ON th1.parent = th2.tid
LEFT OUTER JOIN taxonomy_term_hierarchy th3 ON th2.parent = th3.tid
LEFT OUTER JOIN taxonomy_term_hierarchy th4 ON th3.parent = th4.tid
LEFT OUTER JOIN taxonomy_term_hierarchy th5 ON th4.parent = th5.tid
LEFT OUTER JOIN taxonomy_term_hierarchy th6 ON th5.parent = th6.tid
LEFT OUTER JOIN taxonomy_term_hierarchy th7 ON th6.parent = th7.tid
LEFT OUTER JOIN taxonomy_term_hierarchy th8 ON th7.parent = th8.tid
LEFT OUTER JOIN taxonomy_term_hierarchy th9 ON th8.parent = th9.tid
LEFT OUTER JOIN taxonomy_term_hierarchy th10 ON th9.parent = th10.tid
WHERE ( (tn.tid = '1906') OR (th1.tid = '1906') OR (th2.tid = '1906') OR (th3.tid = '1906') OR (th4.tid = '1906') OR (th5.tid = '1906') OR
(th6.tid = '1906') OR (th7.tid = '1906') OR (th8.tid = '1906') OR (th9.tid = '1906') OR (th10.tid = '1906') ))) )AND(( (node.type IN ('1906')) )))
ORDER BY node_title ASC
LIMIT 50 OFFSET 0

Notice (node.type IN ('1906')). If I change this to "cuvant" (the actual type, also used in the previous query for counting) the query is ok.

I forgot to mention that downgrading Views to 3.0 solved to problem.

I have exactly the same problem. After upgrade to 3.1, all my custom pages and panels disappeared. Downgrading solved the issue. Any idea?

where is
Panels: 1 top + 2 columns
Panels: 1 top + 3 columns
Panels: 2 columns
Panels: 3 columns
Panels: Teasers, By Term, 3 columns

Thanks for spaming the issue queue.

I'm having this same issue. I create a views context, and I cannot use it in Panels. I can create a Panels Relationship, but not a context.