The reason you’re not seeing the Affiliated Institutions is that you have used up all the available space for Title, Authors and Affiliations. The number of lines allotted to these fields are fixed by the iPoster design and if you have too many lines, it will hide the bottom of the area.
If you have a very long Title with several lines of text, it limits the number of lines you can have for Author names and Institutions. If you have a long list of co-authors that require several lines, it will also push the content down to the limit.
The solution is to keep your Titles as short as possible on the iPoster itself. If you have a very long abstract title, for example, try to abbreviate the title on your iPoster so that it doesn’t require so many lines. Your full abstract title will be displayed automatically on the search screen at the conference.
Likewise, keep your list of co-author names and affiliated institutions brief.
If you have a long list, use the CV Button on the Main toolbar. There’s lots of space there. Visitors will be able to read this information by clicking on the CV Button on your iPoster.