We just released another update for FlexTools - v1.6.1
In the previous version (1.6.0) there was a bug that, under some conditions, could prevent FlexTools from working completely!
Please do the following:
1. Do the Automatic Update.
2. If the Red Update button is still visible after the update, no worries - Restart Sketchup, and the update button will go away.
3. If you are asked for an Activation Key after the update, ignore the message! Restarting Sketchup will solve that too.
Please Let us know if there are any further issues.