CWB Dynamic Column - is it caching former formula definition

Hello,

We have a CWB plan that uses a dynamic column with a formula.  The formula was incorrect, so we corrected it, the problem is, sometimes when values are changed, it calculates the old formula.  For example,

The incorrect formula was column a = column b + column c.

I corrected it to column a = column b / column c.

Sometimes, we observe the old formula being calculated again.  Like it is being cached somewhere.

I deleted all the rows of the formula and rebuilt it with the correct version, but we still get this unusual behaviour.

Has anyone observed this before, and is there a way to flush the old formula once and for all?