Including HX711.h causes watchdog timeout of ESP8266.

My current project combines a server, ftp and spiffs as the file system. All works as expected but I now want to add a weighing scale that can be calibrated and accessed via a html page. However, if I include HX711.h everything still works except the ftp server - any connection causes a WDT reset.

Any ideas how a header file can alter working code?

Mike.
P.S. can't post code as far too big.

Answered my own question,
The header contains the code,
Removing the line void yield(void) {}; fixes the problem.

Mike.