Multithreaded loop execution, the value of the variable is always the first value taken, the value of the variable is not cleared

### Expected behavior

hello,
When the loop is executed, the variable value is cleared at an unprecedented time each time

### Actual behavior

When the second loop is executed, the value of the variable is still the value of the first time

### Steps to reproduce the problem


### JMeter Version

5.5

### Java Version

1.8.0_391

### OS Version

Win11[22631.3737]