I do not feed BML, but I do find my gliders leave the carrots behind on the night I feed mixed vegetables each week - especially if I have given them generous portions.
Try measuring the mixed vegetables you offer. It is very easy to offer more than the recommended 1 TBS per glider. If you stick close to the 1 TBS mixed vegetables and 1 TBS fruit per glider, they are more likely to eat some of everything.
If your gliders are like mine, they will fill up on the corn and peas first - and if I have offered more than necessary they have no room to eat the carrots so they go untouched.
If I limit the serving to the 1 TBS per glider - they eat the carrots also.