Nothing but+Singular/Plural noun+Singular verb

‘Nothing but’ means ‘only.’ It can denote ‘only this thing and nothing else,’ for
example, “Give mother nothing but sugar-free peanut butter. She is a diabetic.” ‘Nothing
but’ can have the sense of ‘very’ or ‘a lot of,’ for example, “It is very often nothing but
our own vanity that deceives us.” and “I wish we’d never hire this chauffeur. He has been
nothing but trouble.” It can also have the sense of ‘nothing more important or more
real than,’ for example, “This so-called Picasso painting is nothing but a fake.”

We also use ‘nothing but’ when we complain about something or talk about something negatively; when it rolls off the tongue, it’s a condemnation of something. In some way, “nothing but” minimizes the subject you are talking about. “He’s nothing but a cheat” means “can’t say anything else about him; that’s all you need to know about him.” It is more emphatic than just calling him a cheat. However, we use ‘nothing but’ when we talk about positive situations or things as well: Pamela has nothing but good things to say about her mother-in-law.  (no resentment about her mother-in-law)

Notice that the expression ‘nothing but’ may be followed by a singular or plural noun, however, in both cases the verb will be singular:
Nothing but goats is seen on the pinnacles of mountain tops.
Nothing but books and magazines pleases her. (here, the subject is nothing and not books and magazines, hence, singular verb)

Remember ‘nothing’, according to the traditional rule, is customarily treated as a singular, even when followed by an exception phrase containing a plural noun:
Nothing but roses meets (not meet) the eye.

There are many actual citations in the Corpus of Contemporary American English (COCA) and Google Books which show a variety of choices for the construction of:

<Negative-Pronoun> but <Plural-Noun-Phrase> <Verb-Singular/Plural>
One COCA example uses a singular verb here:
Maybe Pearl was Hiroshima. Nothing but debating points is to be gained by arguing such things. (PBS Newshour, 1991)
On the other hand, COCA examples use a plural verb instead:
. . . it was almost impossible for Darryl to distinguish the members of the surgical team; nothing but their eyes were visible. (Analog Magazine, 2012)

Example sentences of ‘nothing but’

We could see nothing but snow. (nothing other than snow)
Daniel’s wife is nothing but trouble.  (Daniel’s wife always causes problems)
He’ll accept nothing but the best for his family. (he’ll only accept the best, if it’s anything other than the best – he won’t accept it!)
They had nothing but problems with the laptop.  (They had a lot of problems with the laptop)
He did nothing but hide the truth from his wife.
That’s right – nothing but honest work.
Her expression revealed nothing but dismay.
She said nothing but let her eyes speak.
He came to Hollywood with nothing but the backpack.
They saw nothing but a distant beach and the ocean.
She said nothing but knocked at the door.
She could do nothing but continue to grumble.

Some more example sentences of ‘nothing but’

She got nothing but money from the divorce.
You’re nothing but a joke to me, are you?
He could do nothing but give up smoking.
The entire place smelled of nothing but her.
She had done nothing but cry, complain and faint since the break-up.
Emma’s teachers have been nothing but kind to her since she moved in here.
The next few days will be nothing but snow and rains all over the place.
The Prime Minister has done nothing but evade reporters’ questions for the past hour. Why can’t he be honest with them for once?”
When I say don’t chew tobacco, I have nothing but your welfare in mind.