I am having the same difficulty on tracking the registered mail that normally can be tracked under Pos Malaysia. The tracking ID would be in a format http://www.pos.com.my/postal-services/quick-access/?track-trace#trackingIds=RJ436153021CN regardless if it's EMS or registered mail.
If I want to track the EMS code (that starts with Exxxxxxxx), it has no problem showing up in my app, but when it's registered mail, no matter how much I refresh or change in between "Post Malaysia" or "Post Malaysia (Pos Laju). I have no problem tracking it from (for example) Korea Post or China Post, but when it's added by itself, or under 'Partial Deliveries', it still not showing up.
Attached are the screenshot example of the problem:
Registered Mail from Korea with Partial Deliveries, Pos Malaysia is not showing up. I tried it with the other normal Post Malaysia with the same error. This has been happening since late February until today. If I clear the history before this issue, the Korea Post will show up with no problem, and then nothing shows up for Pos Malaysia.
EMS from Japan to Malaysia has no problem showing up with both country's tracker available (Post Malaysia and Post Malaysia Pos Laju)
The last inquiry in regards of this was answered on April 21. Up until now, there is no fix on it.
I am currently using the version 4.9 (1799) in both of my Android smartphones.
I did not hesitate buying the app because it's worth it. Especially with the sync between devices.I kindly hope that this issue with registered mail of Pos Malaysia will be fixed soon.