DRLS not working for user in multiple groups

Hi Experts. 

I have creatd two Dynamic RLS group and the users 1 and User2 are part of two groups.
I have 50 users and have created Distribution list for all where user1 and user 2 are part of that group.
There are couple of issues I am facing.

1) When the user 1 and user 2 are added to one RLS group then the remaining 48 users are unable to see the report. I have added the Distribution list then the remaining 48 users were able to see.
How to solve this and what could be the issue?

2) If the User 1 and User 2 were added to both the RLS groups then they are able to see all the data which I have filtered in RLS group 1 and RLS group 2.

For example:

User1 assigned to RLS Group1 where Country =" USA"
User2 assigened to RLS Group2 where Country = " UK"

The User1 and User2 are part of Distibution list.

1) If the User1 is added to the Group in the PBI server then the User2 + remaining 48 users in the Distribution list are unable to see the report while user1 is able to see the report

2) If the User1 is added to the RLS Group 1 and Group 2 then the users able to see other countries like "Aus", "China" and also "USA" and "UK"

Really apprecaite your help on this.

Thanks,
Vicks