Your where condition that checks for equality for utcdt converted to a date is SARGable, but uses a dynamic seek.
The problem is that these hidden implicit conversions can result in inaccurate cardinality and distribution estimations at any stage of the plan. So, even if you get a seek, the plan might be way off overall. - Dynamic Seeks and Hidden Implicit Conversions - Paul White
Try converting your where condition to an explicit range and see if there is any improvement:
select *
from Tick.X_H
where Symbol = 'donkey'
and utcdt >= convert(datetime2(7),'20110102')
and utcdt < convert(datetime2(7),'20110103')
Based on this answer by Martin Smith the explicit range may reduce unnecessary reads.
References: