I experienced the same thing the other (Friday) night and was getting ready to write this up. Nice work on describing the issue. I found it happened when I set the numbers on a token, then clicked over to a different value with my mouse (the value stayed initially) and then I moved the first token. Bam, number gone, followed by unable to enter a new one. I ended up deleting them and re-adding... hit enter after putting the number on those ones, and they stayed put.