Mine starts out looking that way, and after a brief delay, Firefox shows the folder name field and enables the Add button. Seems that second step is not happening on your Firefox.

Are bookmarks working normally otherwise, you can add individual bookmarks? If in doubt, you can run the "Verify Integrity" function. That's here:

Open Firefox's Troubleshooting Information page using any of these methods:

• "3-bar" menu button > "?" Help > More Troubleshooting Information
• (menu bar) Help > More Troubleshooting Information
• type or paste about:support in the address bar and press Enter

Near the bottom, there is a section titled Places Database -- that's the file which stores history and bookmarks. Click the button labeled Verify Integrity. There may be a 10-15 second delay before results appear.

If all is well, the report that appears below the button should start with:

> Task: checkIntegrity
+ The places.sqlite database is sane
+ The favicons.sqlite database is sane

Does yours say that, or something else? You can select and copy the report, and then paste it into a reply for review and comment.

This is info I get;

t

> Task: checkIntegrity + The places.sqlite database is sane + The favicons.sqlite database is sane > Task: invalidateCaches + The caches have been invalidated > Task: checkCoherence + The database is coherent > Task: expire + Database cleaned up > Task: originFrecencyStats + Recalculated origin frecency stats > Task: vacuum + Initial database size is 5120KiB + The database has been vacuumed + Final database size is 5120KiB > Task: stats + Places.sqlite size is 5120KiB + Favicons.sqlite size is 12736KiB + pragma_user_version is 54 + pragma_page_size is 32768 + pragma_cache_size is -2048 + pragma_journal_mode is wal + pragma_synchronous is 1 + History can store a maximum of 73705 unique pages + Table moz_origins has 1436 records + Table moz_places has 2923 records + Table moz_historyvisits has 51 records + Table moz_inputhistory has 0 records + Table moz_bookmarks has 5513 records + Table moz_bookmarks_deleted has 0 records + Table moz_keywords has 1 records + Table sqlite_sequence has 1 records + Table moz_anno_attributes has 1 records + Table moz_annos has 1 records + Table moz_items_annos has 0 records + Table moz_meta has 4 records + Table sqlite_stat1 has 18 records + Index sqlite_autoindex_moz_origins_1 + Index sqlite_autoindex_moz_inputhistory_1 + Index sqlite_autoindex_moz_bookmarks_deleted_1 + Index sqlite_autoindex_moz_keywords_1 + Index sqlite_autoindex_moz_anno_attributes_1 + Index moz_places_url_hashindex + Index moz_places_hostindex + Index moz_places_visitcount + Index moz_places_frecencyindex + Index moz_places_lastvisitdateindex + Index moz_places_guid_uniqueindex + Index moz_places_originidindex + Index moz_historyvisits_placedateindex + Index moz_historyvisits_fromindex + Index moz_historyvisits_dateindex + Index moz_bookmarks_itemindex + Index moz_bookmarks_parentindex + Index moz_bookmarks_itemlastmodifiedindex + Index moz_bookmarks_dateaddedindex + Index moz_bookmarks_guid_uniqueindex + Index moz_keywords_placepostdata_uniqueindex + Index moz_annos_placeattributeindex + Index moz_items_annos_itemattributeindex > Task: _refreshUI