Hit the Compose button again and check if your signature image shows up now.Close the current window and restart Gmail.Clear the checkmark next to Plain text mode.If the signature image doesn’t show up when you’re compositing an email, disable Plain Text mode. Alternatively, go to Gmail settings and insert the image directly from your Drive folders. If you do that, the image will disappear from your Gmail signature. The most important thing is not to delete that image from your Google Drive account. Click on Insert Image and copy-paste the image link from Google Drive.Change the permission settings to Anyone with the link.Right-click on the image you want to add to your Gmail signature.Unfortunately, there are times when the privacy permissions fail to change and you need to do that manually. Usually, when you insert a Google Drive image in your Gmail signature, its privacy settings automatically switch to “ Anyone can view it“. If the image you’re using in your Gmail signature is stored in Google Drive, check your privacy settings and make sure everyone can view it. Save the signature and exit Incognito Mode. Then, reinsert the problematic image or logo. Sign out of your Google account, and open a new Incognito window. Log Out, Open Incognito Mode and Reinsert the Image

How to use google drive for logo signature