The latest hotfix for Silk Central 13.0 is hotfix 10. It can be obtained via support.
The below issues are resolved in this hotfix (please note all previous hotfixes are included in this hotfix):
RPI 1094099: Renew session ID after login
RPI 1094283: - Fixed creating many upload worker threads - Upload only Test Launch and Source Control plugins to execution servers - Upload plugins only once to execution servers after application server restart
RPI 1094870: Date attribute multi edit is broken: Fix time-zone correction in Find/Replace and Grid View Multi-Edit for test attributes of type date
RPI 1095474: Manual Execution Planning Unit - assign test does not work properly if grouped by one column and sorted by another