I posted about a similar issue on the DB side: Walking ahead or on top of the beat
I can think of a couple of challenges in a big band setting. The first is that in virtually every big band, the wind players all drag. If the rhythm section doesn't propel the band, it will slow down. This gives the wind players the impression that you're the one rushing the beat.
The second problem is if the drummer isn't in the pocket with you.
One suggestion in that thread was to put more arm and wrist motion into my plucking. You might not be able to get away with so much of that on electric, but just a bit might help. And overall (learned this at a music camp that my kids attended this summer), is to let your body be the metronome, i.e., really groove to the music.
At the same time, perhaps a tone setting on your bass with a softer attack and more legato will make it sound like you're not rushing so much.