According to the IMDb, Shawn C. Phillips has worked as

[smakdaddy99999]

According to the IMDb, Shawn C. Phillips has worked as an ADR artist (apparently uncredited) basically doing voicework on a number of mainstream films including Sonic the Hedeghog, The Grinch, and Ralph Breaks the Internet.

Has this been verified?  It's certainly possible that he's been doing mainstream work, albeit uncredited and behind the scenes perhaps doing voice work for background characters for example.    

[Crazybeats]

It is possible but surely he would have mentioned those films at some point? Especially if he did a review for them.

[El Duce]

If he actually did that, there's no way he wouldn't brag about it and try to vlog from inside the studio.

[123456]

It does seem rather odd that he wouldn't mention it even if it was just some small and uncredited voice-over work. Look at the big deal he made out of having a possible cameo in the Bill and Ted 3 end credits, he talked about that for ages and in the end, his cameo didn't even get picked. 

Having said that though, I have a friend who has been an extra for some mainstream films like The Dark Knight Rises and Star Wars and it wasn't exactly difficult for him to get into it. So with Shawn being somewhat close to Hollywood and having a mediocre filmography, I'm quite surprised he hasn't had more "extra" work in mainstream films. 

[Chauncey's Talent Agent]

Chauncey said in a Q&A recently that he doesn't have any interest in uncredited work without any lines. He wants to sink his teeth into his characters, and he believes it would cause him to get stuck in the extra lane. He wants the possibility to break out. He didn't mention this - but I think he prefers the lower budget roles because they are more relaxed. Chauncey hates stress and responsibility. He also said he prefers roles without tight scripts, because learning lines is difficult.

For those reasons - I don't think he would go anywhere near ADR. He wants to be seen.