Since yesterday I can not sync (ESS) my android phone anymore, my partner is having the same issue (both installed via apk). I have version 1.2-27.
I uninstalled and reinstalled, wiped everything and unlinked my sync account. When I attempt to sign in to set up ESS again I get the following error:
sign in error
java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.
Sync from iOS still works for me.
I looked up the error and found a few unrelated programs where apparently the solution was to fix something server-side. Any ideas?