Red flags keep popping up over Apple's new fingerprint sensor for its next iPhone.

Pacific Crest Securities analysts said in a note to investors Sunday that Apple's component suppliers were struggling with a new fingerprint sensor. That sensor is expected to go under the phone's cover glass to let Apple remove the iPhone's current home button and create a larger display.

The investment bank claimed these manufacturing issues could result in shortages or delays in availability for the new, 10th anniversary iPhone, which is expected to see huge demand. Otherwise, Apple might scrape the new fingerprint sensor in the device, which is expected to be announced in September.

Pacific Crest isn't the only place reporting such problems. Cowen analyst Timothy Arcuri last week said issues came up from putting the sensor under the phone's cover glass.

If the new sensor doesn't work, Apple may decide to move the sensor to the back of the phone, similar to the new Samsung Galaxy S8. A mockup showing this possibility surfaced online last week.

Apple didn't immediately respond to a request for comment.