Xaml strange behavior: textbox changed flowdirection -

i have question - have textbox in application. 1 minute other, changed flow direction lefttorigt righttoleft. of course checked it's style , (because other textboxes, inheriting same style, behave in normal way.

i can't explain myself - there can make behave again? tried setting flow direction explicitly nothing changed.... unfortunately can't find answers on net...

update xaml looks this:

                    <textbox x:name="m_tbmaschine"                       margin="0 15 10 15" grid.row="2"                      materialdesign:textfieldassist.hint="maschine"                       materialdesign:textfieldassist.hintopacity=".3"                      verticalalignment="bottom"                      text="{binding path=aktuellemaschine.maschinebezeichnung,                                          validatesondataerrors=true,                                          updatesourcetrigger=propertychanged,                                          isasync=true}"                      style="{dynamicresource tboxhintbase}"                       isenabled="{binding editierbar, isasync=true}" /> 

and style based on:

    <style x:key="tboxhintbase" targettype="{x:type textbox}" basedon="{staticresource materialdesignfloatinghinttextbox}">           <setter property="verticalcontentalignment" value="bottom"/>           <setter property="verticalalignment" value="center"/>           <setter property="horizontalalignment" value="stretch"/>          <setter property="materialdesign:textfieldassist.hintopacity" value=".8"/>     </style> 

cheers veronica

found reason, though don't understand how cause such kind of behavior... maybe can explain?

 text="{binding path=aktuellemaschine.maschinebezeichnung,                                      validatesondataerrors=true,                                      updatesourcetrigger=propertychanged,                                      isasync=true}" 

removing isasync property changed textbox's behavior original state :)