The tech giant is having issues with “LED backlight leakage” and may be forced to release the handset in October instead of September, Morgan Stanley analyst Katy Huberty wrote to investors this week. The two other devices Apple is reportedly planning to launch this year are still on track for a September release, according to Huberty. Barron’s earlier reported on the note.

Apple has been rumored for months to be working on three new iPhones for this year. The cheapest of them will be an LCD-based iPhone that could come with a design reminiscent of last year’s iPhone X. But unlike the others, it would feature an LCD screen that would be cheaper to produce. A successor to the iPhone X, as well as an iPhone X Plus with a 6.5-inch screen, are also said to be in the works. Those smartphones will have OLED screens, according to reports.

The problem Huberty reported on centers on the LCD iPhone’s backlighting. Since the other two devices have OLED screens that don’t require the LED backlighting, they’re not affected.

According to Huberty, Apple, which is expected to unveil the smartphones in early September, will release the higher-end models sometime that month. The LCD model was initially slated for a six-week delay but is now expected to only be delayed by four weeks.