run this and that should take care of it for you.
UPDATE `xf_xa_sc_category` SET `content_message` = '' WHERE `content_message` = 0
No, there is nothing to fix (the solution to your issue is running that query on your DB). There is no code in Showcase that sets that particular field to 0 (default is and always has been '' empty), nor is there is anything in the XF1 >> XF2 upgrade updates that field (cept the field name change). Somehow (mystery), your particular DB has that field populated with 0 (for reason's I have no idea, but its not Showcase that set that).Is it something that you will fix it in next release
SELECT `title`,`category_content` FROM `xf_nflj_showcase_category`;
UPDATE `xf_nflj_showcase_category` SET `category_content` = '' WHERE `category_content` = 0