Can’t save options

Hi, I was using your plugin for years and eveything was great, but now I wanted to change Checkout notification text, but after saving there was notification about saved changes, but the text was the same as before. I logged into phpmyadmin and checked the wp_options option: woocommerce_wc_pickup_store_settings
value of this field was:
a:16:{s:7:"enabled";s:3:"yes";s:19:"enable_store_select";s:3:"yes";s:5:"title";s:30:"Odbiór w sklepie stacjonarnym";s:10:"costs_type";s:4:"flat";s:5:"costs";s:4:"0,00";s:15:"costs_per_store";s:2:"no";s:15:"stores_order_by";s:5:"title";s:12:"stores_order";s:4:"DESC";s:13:"store_default";s:0:"";s:21:"checkout_notification";s:383:"Podstaw? wydania paczki jest podanie sprzedawcy inicja?ów klienta oraz numeru zamówienia otrzymanego w komunikacie e-mail, potwierdzaj?cym jego realizacj?. Zamówienie b?dzie dost?pne do odbioru w sklepie stacjonarnym w ci?gu 2/3 dni roboczych od momentu nadania jej statusu "zrealizowany". Paczka b?dzie czeka?a na Ciebie w sklepie przez maksymalnie 10 dni roboczych. ";s:18:"hide_store_details";s:2:"no";s:18:"external_bootstrap";s:2:"no";s:21:"external_font_awesome";s:2:"no";s:9:"local_css";s:2:"no";s:15:"disable_select2";s:2:"no";s:14:"plugin_version";s:0:"";}

So I change only text in checkout notification. But after reload in settings page there is all default settings, with no checkout notification. So I tried to change settings, this time, after saving, nothing changed either.

I tried to put original code to phpmyadmin (as above), but settings are still like default, not like mine.

Version of plugin: newest – 1.7.0

The page I need help with: [log in to see the link]