Protractor stale element reference when using the each() method

I am getting the error below as a result of using the each() method in protractor. It has worked fine in the past but is now consistently failing with this error.

Failed: stale element reference: element is not attached to the page document

element.all(bars).each((element) => element.getCssValue('width'))

Is there an alternative or a reason why this might be?

(For clarity, all I want to do is to get the width of each element in a set of web elements called bars.)

Thanks!

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