Have overlooked this little hyphen :/

_locales/de/messages.json

@@ -248,7 +248,7 @@
         "message": "Eine Spende (Schenkung) für den ClearURLs Urheber.",
         "description": ""
     },
-    "clipboard_copy-link": {
+    "clipboard_copy_link": {
         "message": "Link-Adresse kopieren",
         "description": ""
     }

_locales/en/messages.json

@@ -248,7 +248,7 @@
         "message": "A donation for the ClearURLs creator.",
         "description": ""
     },
-    "clipboard_copy-link": {
+    "clipboard_copy_link": {
         "message": "Copy Link Location",
         "description": ""
     }

core_js/context_menu.js

@@ -23,7 +23,7 @@
 
 browser.contextMenus.create({
     id: "copy-link-to-clipboard",
-    title: translate("clipboard_copy-link"),
+    title: translate("clipboard_copy_link"),
     contexts: ["link"],
     icons: {
         "16": "img/clearurls_16x16.png",

manifest.json

@@ -1,7 +1,7 @@
 {
     "manifest_version": 2,
     "name": "ClearURLs",
-    "version": "1.5.6",
+    "version": "1.5.7",
     "author": "Kevin R.",
     "description": "Remove tracking elements form URLs.",
     "homepage_url": "https://gitlab.com/KevinRoebert/ClearUrls",