Autofill not working with Aegis Authenticator

Thanks for giving that a try NoxStellaris​.

I'm not completely familiar with the Aegis app and how it saves your information. If it's saved to the cloud you could try reinstalling the app. If it's saved locally I wouldn't recommend this as a first step as you could lose your 2FA tokens. 

With that in mind I'd like to ask you to try creating a new Aegis item in 1Password to see if the behaviour is any different. 

1.  Open and unlock 1Password for Android.
2. Copy your Aegis password.
3. Tap the "+ New Item" button and create a new Login item
4. Paste your password into the password field, then save the item (it may also be helpful to name the item something distinct).
5. Open the Aegis app, tap the password field, then select "Open 1Password".
6. Search for and select the newly created item, then tap "Always Allow". 

Does the password from the new item fill as expected? Let us know how that goes and thanks again!