Successive financial reports from the Apple ecosystem suggest that iPhone X sales are lower than expected, while highlighting the disproportionate influence that one device maker has over the fortunes of the whole business. The latest in a string of suppliers whose results have apparently been affected by lower than anticipated iPhone X production is Austria’s AMS, which supplies optical sensors to manage color, brightness and even 3D. AMS has issued a warning about negative operating margins, which local analysts blamed on low iPhone X volumes. Guenther Hollfelder, an analyst with Baader Helvea AG, wrote in a client note that AMS’s second quarter guidance “corresponds with about 20-25m less iPhone X units based on our calculations”. The sensor maker said its…