To Reproduce:
1. Open 'ReplaceImage.cs' in the attached project remove the first (WWW) line in the coroutine, change the last line to .. = tex. , change the yield statement to WaitForEndOfFrame().
2. Run, observe that the texture is not changed, editing any RawImage property in inspector updates the texture.
3. This only happens if the yield statement is called before the texture is changed and also the yield takes has to take more than a single frame. If the texture is assigned in the same frame , e.g. after 'WaiForFixedUpdate()', it's updated successfully.