Copy, paste (CTRL + SHIFT + C, CTRL + SHIFT + V) disabled upon start

System:
Sakura 3.8.3
IceWM 2.7.0 (startx, no login manager, no polkit, OpenRC)
OpenRC 0.42.1
Parabola GNU Linux

Description of the issue:
When I do a [CTRL] + [SHIFT] + [c] or [CTRL] + [SHIFT] + [v] , I only get the equivalent for [CTRL] + [C] or [CTRL] + [V]. Then, if I open a new tab with [CTRL] + [SHIFT] + [t], and do the same, it works in the new tab, but sometimes not in the first one.

Steps to reproduce:
Launch sakura with dmenu
a. Try to copy
   1. Launch sakura
   2. Select text in the terminal
   3. Try to copy with [CTRL] + [SHIFT] + [c]
   4. You get ^C
b. Try to paste
   1. Open an application and copy some text
   2. Launch sakura
   3. Try to paste with [CTRL] + [SHIFT] + [v]
   4. You get ^V
c. Workaround
   1. Launch sakura
   2. Open a new tab with [CTRL] + [SHIFT] + [t]
   3. Select text in the terminal
   4. Copy with [CTRL] + [SHIFT] + [c]

Desired behaviour (how do I achieve this?):
1. Launch sakura
2. Select text in the terminal
3. Copy with [CTRL] + [SHIFT] + [c]
4. Paste with [CTRL] + [SHIFT] + [v]

Debugging info:
I get this when I launch sakura from within sakura:
(sakura:14701): VTE-WARNING **: 10:32:57.076: (../vte/src/vtegtk.cc:2517):int vte_terminal_match_add_regex(VteTerminal*, VteRegex*, guint32): runtime check failed: (_vte_regex_has_multiline_compile_flag(regex))

(sakura:14701): VTE-WARNING **: 10:32:57.076: (../vte/src/vtegtk.cc:2517):int vte_terminal_match_add_regex(VteTerminal*, VteRegex*, guint32): runtime check failed: (_vte_regex_has_multiline_compile_flag(regex))