Last summer, members of Snap’s growth team presented CEO Evan Spiegel and other executives with worrying data showing user growth had slowed sharply. In one week, the company had lost 1 million daily active users, out of its total of around 150 million.

The growth team spelled out to Mr. Spiegel a number of likely causes. Among the top factors was Instagram’s recent launch of its copycat feature Stories, the team said. But Mr. Spiegel initially refused to accept there was a growth problem at all, according to two people familiar with the matter. Instead, he asserted the user slowdown was due entirely to a recent move Snap made to deactivate an old version of the Android app, which meant some Android users had been cut off. He told other executives the data itself was flawed, according to the people.