today i find the negative optional price is treated as positive value. but in earlier version it was correct.
Is the caused by un-compatible with latest woocommerce version 3.7 or bug in latest version?
I find the absolute negative (Not in percentage) works in filed type of checkbox input. but the negative percentage value does not work in filed type of select input.
But some days ago, it was not like this. i cannot remember the version number.