Time in Zones Does Not Add Up To 100%

Question

I just got back from a run, and sync'd my Forerunner 225 using Garmin Express 7.28. 
 When reviewing my run in Garmin Connect, I noticed my "Time In Zones" did not appear to be complete or accurate. 
 Normally, the time for all zones should add up to 100%. 
 Here are the actual numbers from todays run - 
 Heart Rate Zones

Zone 5 > 156 bpm &bull; Maximum 0:00 0%

Zone 4 131 - 155 bpm &bull; Threshold 18:22 38%

Zone 3 112 - 130 bpm &bull; Aerobic 4:18 9%

Zone 2 95 - 111 bpm &bull; Easy 3:11 6% 
 
 Zone 1 78 - 94 bpm &bull; Warm Up 0:00 0% 
 
 That only adds up to 53% 
 
 That leaves 47% of my run unaccounted for, and no way to know what zone(s) it was run in. 
 
 Does anyone have any idea why this may have happened, or how to fix it? 
 
 It's not going to be very good as far as tracking my progress this season if this keeps occurring.