Hi, new to LRTimelapse, I had some problems importing LR converted jpg dng's into LRT4. Turns out that on import in LRT4 the sidecar xmp's are not created even if 'initialize after import' is ticked.
Now I convert the jpg's in LR and after conversion save the metadata in LR. This creates the required sidecars.

This sounds a bit strange to me. Please note that LR always embeds any XMP data into DNG or JPG files. So after saving Metadata in LR, you won't see the Side car files. LRTimelapse however, saves XMP data as side car files. So if you load a DNG sequence into LRTimelapse (make sure to not use the importer, if the sequence is already on the harddrive, just open it from the folder selector on the left then) - LRTimelapse will automatically initialize that sequence. If you save in LRTimelapse then, LRTimelapse will create sidecar XMP files.
Both programs (LRT and LR) will read what ever is never - embedded or sidecar XMP.