ADMISSION: MIDI novice and stumbling through things blindly.
 
I have a set of drum loops, including singles (separate kicks, snares, etc).
 
When I find a MIDI clip I like, I naturally want to it to repeat throughout the song (adding fills and such later).
 
When I use either groove loop or step sequence tools, X2 seems to add a bit of blank time to the end of the clip, which makes the first beat of all subsequent loop segments to come in late (e.g., if using 4/4 time and the original clip has four beats, the fifth note comes in around the 1/8th point of the second measure).
 
I suspect there is something basic about clips, loops, sequences or X2 I am missing. It appears that you should be able to convert a clip to a loop and stretch it as far right as you like, but for now it botches-up the sequence.
 
If it makes any difference, the loops came from Prosonic Labs.

If the clip isn't the right length or you have multiple clips that start or end at odd times, select the range of time you want to loop and choose Clips > Bounce to Clips. Once you have a clip that is the right length, use ctrl+l then drag it out as long as you like.

gswitz
If the clip isn't the right length or you have multiple clips that start or end at odd times, select the range of time you want to loop and choose Clips > Bounce to Clips. 

Yes. As far as SONAR is concerned, a clip starts when the first note starts and ends when the last note ends. If you select the range of time or slip-edit the end (or beginning) to the right length, then bouncing to clip defines an end or beginning other than the note itself.