How to fix Less compilation?

Question

css

I'm working with Magento 2.2, the latest Less is installed, suddenly on some pages it stopped compiling Less to css, error

OperationError: Operation on an invalid type
in catalog.css on line 1181, column 3:

1180.grid[data-mode='grid'] .grid-item.big {
1181  -webkit-flex-basis: -webkit-calc(calc(100% / 5) * 2);
1182  -ms-flex-preferred-size: calc(calc(100% / 5) * 2);

What to do? How to fix?

Answer 1

-webkit-flex-basis: calc( ~"100% / 5 * 2" );

Answer 2

(100% / 5) * 2 = 40%
Why calc for this?