Tempo Detection problem

I find Tempo Detection sometimes works, sometimes doesn’t - totally random. Extremely frustrating. If anyone can shed any light onto this I’d be grateful - I’m attaching a screen shot of a tempo detection attempt - you’ll see that the tempo points always appear sometime before (or after?) the waveform, which is a rim-shot click and very defined. What’s going on? Before the tempo detection process, the first event was bang on the start of bar 7. (I’ve even tried moving everything to start of bar 1 to get rid of any tempo up to the detection point, if you get my drift, exactly the same thing happens…) Any info greatly appreciated, thanks, MD