In a video shared to Twitter on Tuesday, the drummer claimed Calm was "robbed" of the top spot this week.
"I just want to say I appreciate you contesting and fighting for our number one record in the U.S.," he said. "We're left with the number two spot this week and, may I add, that I think it's absolutely astonishing and incredible that we're even at the top of those charts in the calibre of artists that are there with us.
"Records were released a week early that we had no control over, which is very disappointing. Quite honestly, my heart broke when I found out about that."
The group lost 10,000 sales towards the chart when a batch of records were dispatched to fans early, resulting in Calm debuting last week at number 62.
Ashton added that other artists whose records were released early have had their charts positions "amended" but "it seems like that isn't going to happen to us".
"I want you to know that I'm extremely proud of this fan base for having a voice," the 25-year-old insisted. "I love you guys. Remain sincere, keep voicing when things are wrong and I'll try and be as brave as you are."
Ashton also tweeted that he was "apprehensive" about sharing his thoughts on the chart fiasco.
"I think I've censored myself fairly well. I feel fearful to speak up about the albums that went out early for fear or losing partnership with media outlets," he added.
The group were beaten to the summit by The Weeknd's hit album After Hours.
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