It happens really often. Especially in the lobby you can realize it by activating streamer mode and throwing tomatos at defaults. In the feed it will often say a skin which is just not loaded and thats why its always a ramirez default.
If you see this happen while in game please report it under the Feedback button in the game menu. Then please see if you are able to save/share the replay file with myself so I can send it over to the team. The report helps us gather your player logs for information about the issue.