IAP conflicts with AdMob

Hello, gentlemen! Please, help me!

I have +999 error when I try to build a simple Android project (with only a Canvas and buttons) after import IAP. Some solution for this? (Working normally in the editor)

Thanks in advance!

I tried to reimport all but the same errors.

Unity 2020.1.2f1 / IAP 2.2.6

Spoiler

EDIT:
I managed to reproduce the error. It occurs after importing the Google AdMob 5.4.0 package. Is there any reason to cause the conflict with IAP?

EDIT²:
I believe I have confirmed it, because as soon as I import the .package from Google AdMob, it is no longer possible to generate a build without errors. They work or one or the other, both don't.

We can fix this conflict? With only IAP, the build is a success (or vice-versa), but after import AdMob (or vice-versa) package, errors, errors and more errors... :/

I using Google AdMob 5.4.0 and IAP 2.2.6 with Unity 2020.1.2f1

 

UPDATE:
I have no idea if it was because I deleted the billing-3.0.1.aar file or because I reimported everything, but apparently, selecting "reimport all", sometimes works, sometimes not, but it is a solution to this conflict through AdMob, IAP and Google Play Services.

 

Thanks by your response! "Reimport all" works well!