Extension Manager Error While Installing Language Extension (bb01ff21_dict-sr.oxt)

While adding extension bb01ff21_dict-sr.oxt (a Serbian Spellchecker) to the LibreOfficePortable 7.1.2.2 (x86), an Error dialog box appears on the screen with a message:

C:\PortableApps\PortableApps\LibreOfficePortable\App\libreoffice\program\..\..\..\Data\settings\user\uno_packages\cache\uno_packages\lu10984k4b7p.tmp_\bb01ff21_dict-sr(1).oxt does not exist.

'Only for me' installation.

After further Investigation, I've found out that in the directory c:\PortableApps\PortableApps\LibreOfficePortable\Data\settings\cache\ there is just one file (skia.log, 23 bytes) with a content:

RenderMethod: raster
Compiler: Clang

But the directory c:\PortableApps\PortableApps\LibreOfficePortable\Data\settings\user\extensions\tmp\extensions\ contains subtree lu69721refbr.tmp_\bb01ff21_dict-sr.oxt\ with an unpacked .oxt.

Even more, I cannot add any another localization extension to the LibreOfficePortable and haven't got a hyphenation at all. So the portable instance of LibreOffice is absolutely useless for me without localization extensions.