How old are your gliders?
If they are very young the 1 TBS BML, 1 TBS fruit and 1 TBS vegetables is the recommended serving for adult gliders. Young joeys may not eat the full amount until they get a little bigger.
Did you measure your Ice cube trays to see how much each cube will hold? Some make larger cubes than others. It is possible that you are offering more than they can eat.
How many gliders do you have?
If you have only two gliders - cut back on the fruit and vegetables to 1/4 cup (4 TBS) and see if the eat more of the BML. Gliders have very small stomachs about the size of the tip of your thumb. They cannot eat a large amount at one time but eat several times during the night.
Another thing to consider is that many folks have observed that gliders eat less during a full moon. The moon was full 2 nights ago and was still VERY bright last night. That may have contributed to them not eating.
Give them a few more nights and see if their appetites pick up. Gliders will not starve themselves if food is available