diff --git a/ui (gen4)/features/collections.js b/ui (gen4)/features/collections.js
index f278bf25..628b713b 100755
--- a/ui (gen4)/features/collections.js	
+++ b/ui (gen4)/features/collections.js	
@@ -1982,7 +1982,9 @@ module.CollectionTags = core.ImageGridFeatures.Feature({
 					// load local_tags...
 					local_tag_names
 						.forEach(function(tag){ 
-							tags[tag] = new Set(local_tags[tag] || [])
+							tags[tag] = new Set(local_tags[tag] 
+								|| (that.data.tags.__index || {})[tag] 
+								|| [])
 						})
 
 					;(this.crop_stack || [])
@@ -2109,13 +2111,14 @@ module.CollectionTags = core.ImageGridFeatures.Feature({
 							}
 							var t = (c.data || {}).tags || {}
 
+							/* XXX do we need this???
 							c.local_tags = c.local_tags || {}
 							;(that.config['collection-local-tags'] || [])
 								.forEach(function(tag){
 									c.local_tags[tag] = new Set(c.local_tags[tag] || t[tag] || []) })
+							//*/
 						})
 			}],
-		//*/
 	],
 })
 
diff --git a/ui (gen4)/imagegrid/data.js b/ui (gen4)/imagegrid/data.js
index 4458fa26..cff00feb 100755
--- a/ui (gen4)/imagegrid/data.js	
+++ b/ui (gen4)/imagegrid/data.js	
@@ -3399,6 +3399,8 @@ var DataWithTags2Prototype = {
 	},
 	join: function(...others){
 		var res = DataWithTags2Prototype.__proto__.join.apply(this, arguments)
+		!(others[0] instanceof Data)
+			&& others.shift()
 		res.tags.join(...others
 			.map(function(other){ 
 				return other.tags }))
diff --git a/ui (gen4)/imagegrid/tags.js b/ui (gen4)/imagegrid/tags.js
index daa7af5e..3db2db25 100755
--- a/ui (gen4)/imagegrid/tags.js	
+++ b/ui (gen4)/imagegrid/tags.js	
@@ -445,7 +445,7 @@ var TagsPrototype = {
 		return false
 	},
 	has: function(value){
-		for(var v of Object.values(this.__index)){
+		for(var v of Object.values(this.__index || {})){
 			if(v.has(value)){
 				return true
 			}
@@ -754,19 +754,22 @@ var TagsPrototype = {
 
 	join: function(...others){
 		var that = this
-		var index = this.__index
+		var index = this.__index || {}
 		others
 			.forEach(function(other){
-				Object.entries(other.__index)
+				Object.entries(other.__index || {})
 					.forEach(function(e){
 						index[e[0]] = new Set([...(index[e[0]] || []), ...e[1]]) }) })
+		Object.keys(index).length > 0 
+			&& this.__index == null
+			&& (this.__index = index)
 		return this
 	},
 	// XXX create a new tagset with only the given values...
 	// XXX this should support a function...
 	filter: function(values){
 		var res = this.clone()
-		Object.values(res.__index)
+		Object.values(res.__index || {})
 			.forEach(function(s){
 				values.forEach(function(v){ s.delete(v) }) })
 		return res