Cabello later took to Snapchat to apologize to fans, attributing her absence to "anxiety."
"Hi Missouri, sorry I couldn’t finish the set last night," she wrote. "Was having too much anxiety and couldn't finish it."
"I love u. I'm truly sorry," she added.
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The Cuban-born singer also expressed her tiredness shortly before the group hit the stage at the Hollywood Casino Amphitheatre.
"Just wanna sleep for 3 days," she tweeted.