Also be aware that the “routed length” indicator in the status bar is a coarse guide that doesn’t necessarily match the length tuner values in all cases. Routed length sums up the lengths of all segments on a net, whereas the length tuner attempts to measure the distance between two pads (i.e. the source and sink).
This would cause a discrepancy if the net in question branches, because both branches would be included by the routed length indicator but not by the length tuner. The length tuner also has some other tricks to increase accuracy that aren’t used by the routed length calculation, such as using the effective electrical path through pads rather than following track segments through pads, and using the effective via height rather than total via height (for example if your net follows a via from layer 1 to layer 2, the length tuner would only include the fraction of the via height between L1 and L2 rather than the entire via height).
There could still be bugs (see the bugfix/improvement linked above) but it’s expected that there will be a difference between the two values because they measure subtly different things.