Thanks for your update.
On analyzing based on the provided update, it seems that you are using localization in your application. And we suspect that you might not included updated default resource file of SfDataGrid. And we have prepared simple sample with the updated resource file and filtering is working fine at our end.
Please find sample for the same from the link below
Further, we are facing issue in text rendering for “ok” and “cancel” buttons shown in FilterPopup in the version 184.108.40.206. We are now validating this issue from our end and we will update you with more details on 21st August,2019.
We will appreciate your patience until then.