SDL TMS and Language Resource Template

Hi,

I need to update segmentation rules of a customised language resource that is used for a File Type on SLD TMS (12.).

I downloaded it from TMS (*.sdltm.resource file), load it in Studio, do the changes (only adding one simple segmentation rule) and upload the updated *.sdltm.resource back  into TMS.

For some unknown reason, the updated File Type systematically generates recoveries on TMS: 

NullReferenceException : Object reference not set to an instance of an object. : Caused by NullReferenceException at Sdl.LanguagePlatform.TranslationMemoryApi. Object reference not set to an instance of an object. : at Sdl.LanguagePlatform.TranslationMemoryApi.LanguageResourceEntityCollectionDataAccessor.<>c__DisplayClass7_0.<GetLanguageResource>b__0(LanguageResourceEntity resource) at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source, Func`2 predicate) at Sdl.LanguagePlatform.TranslationMemoryApi.LanguageResourceEntityCollectionDataAccessor.GetLanguageResource(LanguageResourceType type, CultureInfo culture, Boolean fallback) at Sdl.LanguagePlatform.TranslationMemoryApi.LanguageResourceEntityCollectionDataAccessor.GetResourceStatus(CultureInfo culture, LanguageResourceType t, Boolean fallback) at Sdl.Core.LanguageProcessing.Resources.CompositeResourceDataAccessor.GetResourceStatus(CultureInfo culture, LanguageResourceType t, Boolean fallback) at...

If I restore the original Language Resource, no issue.... Any idea on what could be the problem?  Is there incompatibility between editing such file in Studio and being able to use it on TMS?

Thanks.