I wasn't able to reproduce your issue as my added static routes were there and they were working (and they were in the table when i executed route -n). Even after the reboot, my route was there and didn't disappear anywhere.
Could you please tell me, have you updated to 07.00 with kept settings or was that a clean install without keeping the settings?
Also, there were no additional reports around this issue of yours, so it seems that you're alone who's having this issue. Please reflash your router with the same firmware without keeping the settings and try configuring everything again, as I can't reproduce the issue.