Created attachment 33535 [details]
JMeter testplan with example of the bug and example of the workaround.

When you want to use the If Controller when your variable == 'something', this does not work after 'Start next Thread loop'. 

Situation:
${VariableForIf} = IfIsYes

If controller condition: "${VariableForIf}" == "IfIsYes"
In the If controller there is a assertion: When "${VariableForIf}" == "IfIsYes" the assertion will fail.
Then 'Start next thread loop' is applicable.
Second time the If controller is not touched.

Expected situation:
As long as ${VariableForIf}" == "IfIsYes" the flow is going into the If controller, the assertion will fail, and again and again.

Work arround: check out 'generate parent sample' of the Transaction Controller.

See attachment for an example.