1) Open LibreOffice
2) Open Impress
3) Click on 'Master Slide' tab of sidebar
4) All thumbnails in 'Available to Use' section will say 'Preparing preview'
5) Click on 'Custom Animation' tab and then 'Master Slide' tab and some thumbnails will appear while others wont.
Regression as this worked correctly in 4.4.
Build ID: 943af6cd6f07c2e0ccd067f661d8dc664eea1e4b
CPU Threads: 2; OS Version: Linux 4.2; UI Render: default;
TinderBox: Linux-rpm_deb-x86@71-TDF, Branch:master, Time: 2016-02-21_01:49:02
Locale: en-US (en_US.UTF-8)
*** This bug has been marked as a duplicate of bug 94370 ***