Consider the sentence in two parts: 1.
Reports are now coming in.
2.
There is trouble at yet another jail.
Or look at it in a conversation:
"We're now getting a lot of reports.
" "Oh, really?
What do they say?
" "There's trouble at yet another jail.
"
In the sentence, of is used to indicate the reports' subject matter.
Several different words could be used to express the same thing: Reports are now coming in of trouble at yet another jail.
Reports are now coming in about trouble at yet another jail.
Reports are now coming in concerning trouble at yet another jail.
Reports are now coming in in relation to trouble at yet another jail.
Reports are now coming in on the topic of trouble at yet another jail.
Reports are now coming in that say there is trouble at yet another jail.
Syntactically, reports are not the same thing as trouble .
It's like a bowl of ice cream .
The bowl contains ice cream, but the bowl isn't the ice cream.
You can't just remove of (without replacing it with something else) and have the phrase make sense.
ell.stackexchange.com/users/73781/Jason Bassford
The role of "of" is clearer if you move "are now coming in" to the end of the sentence: Reports of trouble at yet another jail are now coming in.
Or, reduce the sentence to: Reports of trouble are coming in.
We have reports of trouble.
"Of" says what the reports are about.
You can't remove it.
Compare "reports of trouble" with "pictures of boats", "sales of houses", etc.
Without "of", "Reports trouble are coming in" doesn't work.
(You could say: "Trouble reports are coming in", although that wouldn't work with the longer description "trouble at yet another jail".)
ell.stackexchange.com/users/4491/Boann
I cannot parse this without "of", as the noun phrase "trouble at yet another jail" has nothing to give it a grammatical role in the sentence.
With "of", this indicates the particular meaning of the noun report which takes a complement with "of": a message that something has occurred or been witnessed, without necessarily having any more detail.
This is distinct from the meaning of report when followed by "about" or "concerning", which usually implies a degree of detail.
ell.stackexchange.com/users/1780/Colin Fine
No answers that define what "Reports are now coming in trouble at yet another jail" means: I get the sense that we have some naughty reports that are assaulting more jails or the reports
are not having much success at attacking jails.
(The jails are fighting back?)
This shift is by taking "in trouble" from the "coming in" verb phrase.
Since "at" appears after "in trouble", you get the new "coming at" verb phrase, which basically means fighting or brawling.
The "In trouble" can either mean one has been caught and will be punished or some issue has come up and failure is becoming more likely.
ell.stackexchange.com/users/88984/IMarvinTPA
Reports are now coming in of trouble at yet another jail.
The standard order here would be: Reports of trouble at yet another jail are now coming in.
In newspeak, reports of trouble, reports of rioting, reports of [whatever] are common usages.
at yet another
just means: there is
has already been reports of trouble at one jail.
This is the second.
Yet another child almost drowned at the lake.
[there was already one]
This sounds like a reporter speaking live, and that sometimes causes unusual word order.
But it is not wrong for speech.
ell.stackexchange.com/users/33113/Lambie
What is the meaning of "of trouble" in the following sentence:   Reports are now coming in  of trouble  at yet another jail.   Does it mean "Reports(=trouble at yet another jail) are now received" ?  What is the difference between without "of":   Reports are now coming in trouble at yet another jail.    and with "of":   Reports are now coming in  of  trouble at yet another jail.
What is the meaning of "of trouble" in the following sentence?
ell.stackexchange.com
<meaning>
ell.stackexchange.com/questions/204365
ell.stackexchange.com/users/43907/user22046
In the sentence,  of  is used to indicate the reports' subject matter. Without "of", "Reports trouble are coming in" doesn't work. The standard order here would be:  Reports of trouble  at yet another jail are now coming in.   In newspeak, reports of trouble, reports of rioting, reports of [whatever] are common usages.   The sentence doesn’t make any sense without "of" since "of" explains what the reports are about. 
The sentence doesn’t make any sense without "of". "Of" explains what the reports are about. 