This script returns correct results ...
-- "StartupDisk:System:Library:Filesystems:" is selected
tell application "Finder"
activate
set selList to get selection
if (count items of selList) ≠ 1 then return
end tell
set itemPath to (item 1 of selList) as text
tell application "Finder" to open window of folder itemPath -- correct folder is opened
However, this script opens the wrong folder ...
-- "StartupDisk:System:Library:Filesystems:" is selected
tell application "Finder"
activate
set selList to get selection
if (count items of selList) ≠ 1 then return
end tell
set itemPath to (item 1 of selList) as text
set itemAlias to (item 1 of selList) as alias
tell application "Finder" to open window of itemAlias -- INCORRECT folder is opened
-- "StartupDisk:Library:Filesystems:" is opened
Indicating that the Finder is having a problem with aliases.