Strange behavior of ~

[cideM]

I have the following configuration:

        let g:sandwich_no_default_key_mappings = 1
        silent! nmap <unique><silent> gd <Plug>(operator-sandwich-delete)<Plug>(operator-sandwich-release-count)<Plug>(textobj-sandwich-query-a)
        silent! nmap <unique><silent> gr <Plug>(operator-sandwich-replace)<Plug>(operator-sandwich-release-count)<Plug>(textobj-sandwich-query-a)
        silent! nmap <unique><silent> gdb <Plug>(operator-sandwich-delete)<Plug>(operator-sandwich-release-count)<Plug>(textobj-sandwich-auto-a)
        silent! nmap <unique><silent> grb <Plug>(operator-sandwich-replace)<Plug>(operator-sandwich-release-count)<Plug>(textobj-sandwich-auto-a)

        let g:operator_sandwich_no_default_key_mappings = 1
        silent! map <unique> ga <Plug>(operator-sandwich-add)
        silent! xmap <unique> gd <Plug>(operator-sandwich-delete)
        silent! xmap <unique> gr <Plug>(operator-sandwich-replace)

        silent! omap <unique> ib <Plug>(textobj-sandwich-auto-i)
        silent! xmap <unique> ib <Plug>(textobj-sandwich-auto-i)
        silent! omap <unique> ab <Plug>(textobj-sandwich-auto-a)
        silent! xmap <unique> ab <Plug>(textobj-sandwich-auto-a)

        silent! omap <unique> iq <Plug>(textobj-sandwich-query-i)
        silent! xmap <unique> iq <Plug>(textobj-sandwich-query-i)
        silent! omap <unique> aq <Plug>(textobj-sandwich-query-a)
        silent! xmap <unique> aq <Plug>(textobj-sandwich-query-a)

        silent! xmap <unique> im <Plug>(textobj-sandwich-literal-query-i)
        silent! xmap <unique> am <Plug>(textobj-sandwich-literal-query-a)
        silent! omap <unique> im <Plug>(textobj-sandwich-literal-query-i)
        silent! omap <unique> am <Plug>(textobj-sandwich-literal-query-a)

Here's what happens:

~foo~
 ^-- cursor

viq~ selects foo which is correct.

---

~foo~
^-- cursor

viq~ selects foo which is correct.

---

~~foo~~
 ^-- cursor

viq~ selects nothing, which is unexpected

---

~~foo~~
^-- cursor

viq~ selects nothing, which is unexpected