If it was as large as that, then I wonder whether it was Paracolletes crassipes. L. amabilis is only 8 mm long. Something that people often notice about crassipes is that they are always moving, bustling over the flowers - 'busy, busy, busy'.
Ah well it was definitely larger than 8mm. I've added a photo of it near the Lasioglossum (Chilalictus) bicingulatum for comparison. So Paracolletes crassipes seems more likely.