I been using the Windows version for a long time and recently started using a Mac and seems to have the same problem. I'm using the lastest official version of Securecrt (7.2.1 build 443) and OSX Mavericks.
Seems like the problem i'm having is explained in more details in this thread:
https://forums.vandyke.com/showthread.php?t=10456
Is there any solution to this problem except running SecureCRT as root? Changing the tftp server port doesn't work since the equipment i'm using cannot use any other port than udp/69 to access the server.
-gan