I know a lot of people use SEMrush (including myself). I'm been a bit disappointed lately as it appears the accuracy of their positon tracking is pretty unreliable compared to other position tracking services I've used (such as Whitespark). I tested rankings for many keywords and campaigns and found many that were ranked #1 to be reported as #3 or #4 in SEMrush (and no, it's not due to Local Pack being counted as I'm #1 or #2 in local pack too.) I've checked by using the Ad Preview tool in Adwords and setting the search city location and device appropriately, have used I Search From (I Search From: custom location, language, device & personalization Google Search tool to preview ads & results) and have used Whitespark's rank tracker. The latter three were all in agreement on the tests I ran yet in many cases SEMrush was different. Something definitely currently whacky with SEMrush's Position Tracker.
Just throwing this out there for people also using SEMrush to track position. You may want to go double check the results you're getting from them.