I have a datagrid with about a dozen attributes returned. I also have a tooltip defined for this grid which appears when the user hovers over one of the columns. The tooltip window displays one of the attributes of the grid entity. If I don't have the attribute as one of the grid columns, the tooltip window is empty. If I include the attribute as one of the grid columns, the tooltip window shows the contents of this attribute.
I am guessing that this situation occurs because the attribute in question is not part of the state unless I include it as a grid column. I don't use tooltip pages on grids often, so I am wondering if my guess is correct and if this is a known situation.
I've made a similar functionality in the past; I've made a ticket overview on which the user could hover on some columns in order to show a more elaborate description of the ticket. The description wasn't included in any of the data grid columns so in my case I didn't use the attribute I displayed on the tooltip page and this worked fine.
I cannot vouch for newer Mx versions, but I've just checked my app and it's currently is in version 7.5.0 so up untill that version I suspect you shouldn't have any problems.
Did you enable the 'Show tooltip' option on other columns as well (besides the attribute you're referring to in your post)?
I haven't run into this issue before. I'm in 7.15.1 right now so it might be a different case but I have a datagrid that has a tool tip page that shows a list of attributes that are not shown in the datagrid, as well as a listview over an association. I haven't run into an issue yet where certain fields were not showing up in the tool tip page.