Search does not work if there are user assets only from custom folders

Steps to reproduce:

• Make sure you don't have any assets in User Assets (C:\Users\user\Documents\QtDesignStudio\bundles\User)
• Create a 3D project
• In Content library - User assets, click + to add a custom folder
• Select a folder that has image assets
• Once folder is added, try searching assets
• -> search is disabled, cannot type anything
• Add e.g. cubeModel to User assets by right clicking it in Navigator and selecting "Add to Content Library"
• -> now search is enabled