Why does phpspreadsheet read xlsx but not xls?

Question

excel

Good evening.

Installed the phpspreadsheet library. Everything seems to be correct, via composer.
I'm testing with xlsx files, it works correctly - both reads and writes. But xls does not want to read (but writes). Tried to read different xls files, including those generated by him. Tried to run examples from phpspreadsheet documentation with their xls demo files - doesn't work.
When launched, the page simply loads endlessly on the server.
Maybe something wrong with the server? Maybe there are some server requirements?
I have sweb virtual hosting, php 7.2.
I repeat, with xlsx it works for reading and writing, with xls - only for writing. But for reading - no way.
Can, who faced?

UPD: I haven't found a solution yet, I rolled back to using the PHPExcel library - it read everything without any problems. Both xlsx and xls.
It looks like this issue is a known bug in phpspreadsheet . They do not want to support old xls-files.