Android App Bundle from React Native: You uploaded an APK or Android App Bundle with invalid or missing signing information for some of its files

I'm trying to publish an app for the first time to the Google Play Store. I've opted in to Google Play Signing. I know for a fact that I'm signing the Android App Bundle with the right key since, when I'm uploading using another key, the Console will tell me to upload using the other key with the specific SHA1 identifier. However, when I do upload with the correct key, I get this error:

You uploaded an APK or Android App Bundle with invalid or missing signing information for some of its files.

I'm building the app using Android Studio like so: Build > Generate Signed Bundle / APK > Android App Bundle > Choosing my keystore and entering the password > release > Finish

The app is a React Native app built with detached Expo / ExpoKit. Uploading to the Apple App Store works just fine, I only have problems with the Play Store. What am I missing?

Update 1: I now completely deleted the app from Google Play and created a new one. Did not opt in for Google Play Signing this time and uploaded a signed APK. Still the same error.

Update 2: Tried with a completely new keystore and key. Still the same.

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