Metamask notifications aren't displayed as a pop up in the screen

**Description:**
When making a transaction or entering to the interface, the metamask pop up notification isn't displayed. The user can see the notification as a number in the browser extension icon.

**Steps to reproduce:**
1. Go to https://conditionaltokens.staging.gnosisdev.com/
2. Observe.

**Expected behavior:**
The metamask pop up is correctly shown to the user.

**Actual behavior:**
The pop up isn't displayed. The user have to open the notification from the icon.

**Capture**
https://drive.google.com/file/d/19MXJmZqCOhfvMsilLDdWQArFZgMYmQ8U/view?usp=sharing

**Environment:**
Browser: Google Chrome
Wallet: Metamask
Computer: Dell Vostro 5100 14 inches