Reproduces on Safari on latest master (6f53d8cd31486a1e322367d82fb8b87361fece2d).
No issue on Firefox.

Create item:

vfs.file.contents[/tmp/x.txt, ]

x.txt file is attached:
x.txt

Create trigger:

last(/Zabbix server/vfs.file.contents[/tmp/x.txt,])<>0

Name trigger:

{{ITEM.VALUE}.urlencode()}

Result: