With Ultisnips, as soon as I type in insert mode I get "E488: Could not load library function Pyslice_AdjustIndices"

Question

I have Vim 8.2 on Windows with Python 3.6 installed (in the :version menu I see +python/dyn and +python3/dyn). Not only am I unable to use the Ultisnips plugin, I am not able to type in Insert Mode at all, because with every keystroke I get the error E488: Could not load library function Pyslice_AdjustIndices.

Previously, with Python 3.9 installed I got the error could not load library python36.dll and the same behavior (an error after each keystroke).

This is my minimal _vimrc file

set rtp+=~\Vim\vimfiles\bundle\Vundle.vim
call vundle#begin('Vim/vimfiles/bundle')
" let Vundle manage Vundle, required
Plugin 'VundleVim/Vundle.vim'
Plugin 'sirver/ultisnips'
    let g:UltiSnipsExpandTrigger = '<tab>'
    let g:UltiSnipsJumpForwardTrigger = '<tab>'
    let g:UltiSnipsJumpBackwardTrigger = '<s-tab>'
" All of your Plugins must be added before the following line
call vundle#end()            " required
filetype plugin indent on    " required

In the only instance of this issue which I have been able to find the answer was

This error indicates that your Python installation is broken. Try vim -u NONE, then inside Vim try :py3 import sys; print(sys.version) and see if that works.

I tried it and got the error E319: Sorry, the command is not available in this version.