On Windows this will be under your user directory in OWASP ZAP/zap.log
On Linux it will be in ~/.ZAP/zap.log
As you spotted there was a problem with reports on Linux in 1.3.2 but that should be fixed in 1.3.3
btw I only spotted this thanks to a Google alert.
If you report this as a ZAP issue (Issues - zaproxy - OWASP ZAP: An easy to use integrated penetration testing tool for finding vulnerabilities in web applications. - Google Project Hosting) or on the dev mailing list (https://groups.google.com/forum/#!forum/zaproxy-develop) then you'll get quicker responses