diff --git a/src/conversion/upcasthelpers.js b/src/conversion/upcasthelpers.js
index a01022325..719bd7053 100644
--- a/src/conversion/upcasthelpers.js
+++ b/src/conversion/upcasthelpers.js
@@ -405,7 +405,7 @@ function upcastElementToElement( config ) {
 
 	const converter = prepareToElementConverter( config );
 
-	const elementName = getViewElementNameFromConfig( config );
+	const elementName = getViewElementNameFromConfig( config.view );
 	const eventName = elementName ? 'element:' + elementName : 'element';
 
 	return dispatcher => {
@@ -431,7 +431,7 @@ function upcastElementToAttribute( config ) {
 
 	const converter = prepareToAttributeConverter( config, false );
 
-	const elementName = getViewElementNameFromConfig( config );
+	const elementName = getViewElementNameFromConfig( config.view );
 	const eventName = elementName ? 'element:' + elementName : 'element';
 
 	return dispatcher => {
@@ -493,15 +493,15 @@ function upcastElementToMarker( config ) {
 // Helper function for from-view-element conversion. Checks if `config.view` directly specifies converted view element's name
 // and if so, returns it.
 //
-// @param {Object} config Conversion config.
+// @param {Object} config Conversion view config.
 // @returns {String|null} View element name or `null` if name is not directly set.
-function getViewElementNameFromConfig( config ) {
-	if ( typeof config.view == 'string' ) {
-		return config.view;
+function getViewElementNameFromConfig( viewConfig ) {
+	if ( typeof viewConfig == 'string' ) {
+		return viewConfig;
 	}
 
-	if ( typeof config.view == 'object' && typeof config.view.name == 'string' ) {
-		return config.view.name;
+	if ( typeof viewConfig == 'object' && typeof viewConfig.name == 'string' ) {
+		return viewConfig.name;
 	}
 
 	return null;
@@ -684,7 +684,7 @@ function prepareToAttributeConverter( config, shallow ) {
 			return;
 		}
 
-		if ( onlyViewNameIsDefined( config ) ) {
+		if ( onlyViewNameIsDefined( config.view, data.viewItem ) ) {
 			match.match.name = true;
 		} else {
 			// Do not test or consume `name` consumable.
@@ -714,14 +714,17 @@ function prepareToAttributeConverter( config, shallow ) {
 
 // Helper function that checks if element name should be consumed in attribute converters.
 //
-// @param {Object} config Conversion config.
+// @param {Object} config Conversion view config.
 // @returns {Boolean}
-function onlyViewNameIsDefined( config ) {
-	if ( typeof config.view == 'object' && !getViewElementNameFromConfig( config ) ) {
+function onlyViewNameIsDefined( viewConfig, viewItem ) {
+	// https://github.com/ckeditor/ckeditor5-engine/issues/1786
+	const configToTest = typeof viewConfig == 'function' ? viewConfig( viewItem ) : viewConfig;
+
+	if ( typeof configToTest == 'object' && !getViewElementNameFromConfig( configToTest ) ) {
 		return false;
 	}
 
-	return !config.view.classes && !config.view.attributes && !config.view.styles;
+	return !configToTest.classes && !configToTest.attributes && !configToTest.styles;
 }
 
 // Helper function for to-model-attribute converter. Sets model attribute on given range. Checks {@link module:engine/model/schema~Schema}
diff --git a/tests/conversion/conversion.js b/tests/conversion/conversion.js
index e17ce29b2..659e0ae94 100644
--- a/tests/conversion/conversion.js
+++ b/tests/conversion/conversion.js
@@ -301,6 +301,14 @@ describe( 'Conversion', () => {
 			} );
 
 			it( 'config.view is an object with upcastAlso defined', () => {
+				schema.extend( '$text', {
+					allowAttributes: [ 'bold', 'xBold' ]
+				} );
+				conversion.attributeToElement( {
+					model: 'xBold',
+					view: 'x-bold'
+				} );
+
 				conversion.attributeToElement( {
 					model: 'bold',
 					view: 'strong',
@@ -310,22 +318,18 @@ describe( 'Conversion', () => {
 							name: 'span',
 							classes: 'bold'
 						},
-						{
-							name: 'span',
-							styles: {
-								'font-weight': 'bold'
-							}
-						},
 						viewElement => {
 							const fontWeight = viewElement.getStyle( 'font-weight' );
 
-							if ( viewElement.is( 'span' ) && fontWeight && /\d+/.test( fontWeight ) && Number( fontWeight ) > 500 ) {
+							if ( fontWeight == 'bold' || Number( fontWeight ) > 500 ) {
 								return {
-									name: true,
 									styles: [ 'font-weight' ]
 								};
 							}
-						}
+						},
+						// Duplicates the `x-bold` from above to test if only one attribute would be converted.
+						// It should not convert to both bold & x-bold.
+						viewElement => viewElement.is( 'x-bold' ) ? { name: 'x-bold' } : null
 					]
 				} );
 
@@ -363,6 +367,18 @@ describe( 'Conversion', () => {
 					'<paragraph><$text bold="true">Foo</$text></paragraph>',
 					'<p><strong>Foo</strong></p>'
 				);
+
+				test(
+					'<p style="font-weight: 600;">Foo</p>',
+					'<paragraph><$text bold="true">Foo</$text></paragraph>',
+					'<p><strong>Foo</strong></p>'
+				);
+
+				test(
+					'<p><x-bold style="font-wieght:bold">Foo</x-bold></p>',
+					'<paragraph><$text xBold="true">Foo</$text></paragraph>',
+					'<p><x-bold>Foo</x-bold></p>'
+				);
 			} );
 
 			it( 'model attribute value is enumerable', () => {