LR5 has new engine; breaks Timelapse presets
Lightroom 5 had an engine rewrite for Slideshow to allow videos to be added to a slideshow. This completely broke a number of things: sub 1/10 duration which were cheated via Preset for Timelapse, Video frame rates other than 30fps on export, and video export of a large quantities of images with a fast duration.
There is no workaround other than an alternative solution. Remain using LR4 for Timelapse catalogs, using Quicktime Pro, using Premiere Pro, or other video timeline editor.
Until Adobe see fit to correct this, there is no alternative but to go for another solution.