SUMMARY:
It is described in this document a known issue identified in Strategy Web 9.4.1 Hotfix 5. This issue occurs when manipulating the selectors from a document with the ESRI Map widget.
SYMPTOM:
The following error messages appear in Strategy Web 9.4.1 Hotfix 5 when switching the Selector elements from a document that contains the ESRI Map widget:

TypeError: Unable to get property ‘id’ of undefined or null reference at dojo.attr (http://serverapi.arcgisonline.com/jsapi/arcgis/?v=2.4:14:63867) at constructor (http://serverapi.arcgisonline.com/jsapi/arcgis/?v=2.4:48:245969) at Anonymous function (http://serverapi.arcgisonline.com/jsapi/arcgis/?v=2.4:14:31939) at loadESRIMap (http://xxx.xxx.xxx.xxx/MicroStrategy/javascript/ESRIMap.js:1045:21) at xhrCfg.success (http://xxx.xxx.xxx.xxx/MicroStrategy/javascript/ESRIMap.js:895:9) at Anonymous function (http://xxx.xxx.xxx.xxx/MicroStrategy/javascript/bundles/mojo-oivm.js?v=547518441:1:16718) at onreadystatechange (http://xxx.xxx.xxx.xxx/MicroStrategy/javascript/bundles/mojo-oivm.js?v=547518441:1:94021) at Anonymous function (http://xxx.xxx.xxx.xxx/MicroStrategy/javascript/bundles/mojo-oivm.js?v=547518441:1:96955)