Importing from Chrome 155.0.8059.40 64-bit in Opera GX 136.0.6008.111 64-bit on Windows 11 seems to work fine for me, for what it's worth. You can try restarting Windows to see if it helps. Or, make sure both Chrome and Opera GX are updated.
The Chrome importer only imports history and bookmarks these days, so it might just be easier to do things manually.
For passwords, in both Chrome and Opera, goto the URL chrome://password-manager/settings and export your passwords to a CSV file in Chrome and import that CSV file in Opera.
For bookmarks, in Chrome, goto the URL chrome://bookmarks, click the 3 dots at the top left of the page and export your bookmarks to an HTML file. Then in Opera, goto the URL opera://settings/importData, select "Bookmarks HTML file" in the drop-down and point it to the HTML file. Then, goto the URL opera://bookmarks, go in the "Bookmarks Bar" folder and move the imported bookmarks where you want.
For history, you can use an extension to export and import.
For cookies, you can also use an extension to export and import them.
For open tabs in Chrome, before you export your bookmarks, you can right-click on the tab bar and choose "Bookmark all tabs" to bookmark them to a folder. Then in Opera, after you've imported your bookmarks, you can right-click on that bookmarks folder that represents your open tabs and choose "open all in tabs".
