The phrase "are sometimes missing" is correct and usable in written English.
It can be used to indicate that something is not always present or available at certain times.
Example: "In some reports, key data points are sometimes missing, which can affect the overall analysis."
Alternatives: "may occasionally be absent" or "can be lacking at times."
Relationships are sometimes missing from data models.
Doors, windows, bathtubs, appliances and air-conditioning units are sometimes missing the day after they are installed.
The result is not a sweeping history of what has come to be known as "Africa's world war", but a series of intimate and entertaining portraits that are sometimes missing from other accounts.
The deposits of the drowning succession are sometimes missing on the top of the platform, while they are found forming clinoforms along its flanks, evidence that sediment could be permanently swept from the highs in these depositional systems at this stage.
The formal tutorials that come with the program are thorough but flawed: the interaction is limited (it solves some problems for you instead of letting you try to solve them), pieces are sometimes missing or in the wrong position, and a couple of the solutions given are wrong.
It not only adds a dash of colourful modern design to a neighbourhood marinated in its own past but it generously piles on the extras that are sometimes missing from the big chains: breakfast, Wi-Fi and bottled water are all included.
Many recent high-profile police shootings have been legally justified, but there are sometimes "missed opportunities to ratchet down the encounter, to slow things down, to call in additional resources," Chuck Wexler, executive director of the group, wrote in the report. .
This may mean that symptom deterioration and relapse indicators are sometimes missed, and opportunities for promoting self-management lost.
Although competent radiologists will usually make the correct diagnosis, occasionally they will not because small cancers may be unresolved, missed, or misinterpreted as spasm; even "obvious" tumours are sometimes missed.
We found similar clusters in most streptomycetes (S. hygroscopicus was an exception) and sporadically among other morphologically complex genera (but ramS orthologues are sometimes missed in the reciprocal blastp analysis because these genes are very small).
Night showers are sometimes "missed" if you have your face covered in books and realize that it's time to go to sleep.
