Backstop/Chromy breaking when an element has position absolute css property

When a page under test has an element with position absolute property, and this element has no relative parent, Backstop or Chromy (i dont know) breaks.

Here`s the output:

`ChromyJS returned an unexpected error while attempting to capture a selector. TypeError: Cannot read property 'length' of null
at Chromy._screenshotMultipleSelectors$ (/usr/local/lib/node_modules/backstopjs/node_modules/chromy/dist/index.js:1388:27)
at tryCatch (/usr/local/lib/node_modules/backstopjs/node_modules/babel-runtime/node_modules/regenerator-runtime/runtime.js:62:40)
at Generator.invoke [as _invoke] (/usr/local/lib/node_modules/backstopjs/node_modules/babel-runtime/node_modules/regenerator-runtime/runtime.js:296:22)
at Generator.prototype.(anonymous function) [as next] (/usr/local/lib/node_modules/backstopjs/node_modules/babel-runtime/node_modules/regenerator-runtime/runtime.js:114:21)
at tryCatch (/usr/local/lib/node_modules/backstopjs/node_modules/babel-runtime/node_modules/regenerator-runtime/runtime.js:62:40)
at invoke (/usr/local/lib/node_modules/backstopjs/node_modules/babel-runtime/node_modules/regenerator-runtime/runtime.js:152:20)
at /usr/local/lib/node_modules/backstopjs/node_modules/babel-runtime/node_modules/regenerator-runtime/runtime.js:162:13
`