This is a very frustrating Issue and can have 2 reasons.
- The EPG Source is wrong , which is not up to the IPTV Services, rather 3rd Party EPG Provider
- The Timeshift of the EPG is wrong
For the first reason nothing can really be done until the EPG provider fixes it, specially with APKs where you can not change the EPG your self.
For the Timeshift problem, this is quite common and mostly the Issue. The APKs offer you in the Settings to adjust the Timeshift.
Simply adjust it to fit your Time with the EPG and you will have a properly synced and working EPG.