This issue is composed of two recently encountered problems: one for vfs.file.regexp[] and another one for web.page.regexp[].

(A) If item vfs.file.regexp[] is applied on a file with Windows line endings, then \r symbol prevents the $ symbol from matching.

For instance, consider the example below:

$ echo ' C: 8195Mb 5879Mb 2316Mb 28.2' > file.txt

$ zabbix_agentd -t 'vfs.file.regexp[file.txt,"C.* ([0-9]+\.[0-9])$",,,,\1]'
vfs.file.regexp[file.txt,"C.* ([0-9]+\.[0-9])$",,,,\1] [s|28.2]

$ unix2dos file.txt
unix2dos: converting file file.txt to DOS format ...

$ zabbix_agentd -t 'vfs.file.regexp[file.txt,"C.* ([0-9]+\.[0-9])$",,,,\1]'
vfs.file.regexp[file.txt,"C.* ([0-9]+\.[0-9])$",,,,\1] [s|]

$ zabbix_agentd -t 'vfs.file.regexp[file.txt,"C.* ([0-9]+\.[0-9])",,,,\1]'
vfs.file.regexp[file.txt,"C.* ([0-9]+\.[0-9])",,,,\1] [s|28.2]

(B) For web.page.regexp[], the \r character is included into the output by default:

$ zabbix_agentd -t 'web.page.regexp[localhost,,,.*]'
]eb.page.regexp[localhost,,,.*] [s|HTTP/1.1 200 OK

Note how "w" in "web.page.regexp" was replaced by "]". This shows that \r was included into the output.