I just did an assisted attack and on checking the XP total it appears to be applied wrongly and is missing some xp off the final total. I did a few more runs and they all have lower final xp than they should!
The figures are here
Starting xp 145,190
Attack 2,070 x 4
Ally bonus 828
Elite bonus 6,830
Total run xp = 15,938
Add 15,938 to 145,190 and get 161,128, however, the dragon shows 160,050 which is a loss of 1,078 xp.
Anyone else notice or having this problem?