custom css code being removed / no longer saving

Hi.
I have used the plugin for a really long time without issue. Today I made a minor amendment to my custom css set within the plugin settings and when I press save the content of the css window is deleted. I have a copy of it and I re-paste / save and it just clears to blank leaving my pages without any of my tabbed / spoiler colour customisations. I have tried loading with the 2019 theme and no plugins on a test site and have same issue. Any ideas …?

The CSS I had was this (I only changed a spoiler title color then ‘saved’):

<style>
.su-list ul li i {
line-height: 1.5;
}
.su-list ul li {
line-height: 1.5;
}

</style>
<style>
.su-spoiler.my-custom-spoiler {}
.su-spoiler.my-custom-spoiler .su-spoiler-title { background-color: #ca510c; }
.su-spoiler.my-custom-spoiler .su-spoiler-title { color:#ffffff; font-size:15px;}
.su-spoiler.my-custom-spoiler .su-spoiler-content { padding: 1% }
.su-spoiler.my-spoiler-spain-fin .su-spoiler-title { background-color: #16365C; color:#ffffff; font-size: 1.3em; }
.su-spoiler.my-spoiler-spain-fin .su-spoiler-content { padding: 1% }

</style>
<style>
.su-tabs.my-custom-tabs { background-color: #dac68f } .su-tabs.my-custom-tabs .su-tabs-nav span { font-size: 1em }
.su-tabs.my-orange-tabs { background-color: #C5410C } .su-tabs.my-custom-tabs .su-tabs-nav span { font-size: 1.1em }
.su-tabs.my-cream-tabs { background-color: #dac68f } .su-tabs.my-custom-tabs .su-tabs-nav span { font-size: 1em }
.su-tabs.my-teal-tabs { background-color: #669e93 } .su-tabs.my-custom-tabs .su-tabs-nav span { font-size: 1em }

</style>
<style>
.su-tabs.my-new-tabs { background-color: #031a38; }
/*unselected tab*/
.su-tabs.my-new-tabs .su-tabs-nav span { font-size: 1.3; color: #ffffff; font-weight: 700;}
/*try to change unselected tab hover*/
.su-tabs.my-new-tabs .su-tabs-nav:hover span { font-size: 1.3; color: #031a38; font-weight: 700;}
/*course data*/
.su-tabs.my-new-tabs .su-tabs-nav span.su-tabs-current { background-color: #ffffff; color: #031a38; }
/*background to main data*/
.su-tabs.my-new-tabs .su-tabs-pane {
padding: 5%;
font-size: 1.1em;
background-color: ;
}
</style>
<style>
/**shortcodes**/

<style>
.su-spoiler.my-custom-spoiler2 {}
.su-tabs-vertical .su-tabs-nav {
float: left;
width: 15%;
background-color: #031a38;

}
.su-tabs-vertical .su-tabs-panes {
float: left;
width: 85%;

}
.su-tabs-vertical .su-tabs-nav span.su-tabs-current {
background-color: #C5410C;
color:#ffffff ;

}
</style>

</style>
<style>
.su-box {
margin: 0 0 1.5em 0;
border-width: 1px;
border-style: solid;
}
.su-box-title {
display: block;
padding: 0.5em 1em;
font-weight: bold;
font-size: 1.1em;
}
.su-box-content {
border: 1px solid #992224;
background-color: #EEEEEE; /* old browsers */
background: -moz-linear-gradient(center top , #FFFFFF, #EEEEEE); /* firefox */
background: -webkit-gradient(linear, center top, center bottom, from(#FFFFFF), to(#EEEEEE)); /* webkit */
background: -o-linear-gradient(top, #FFFFFF 0%,#EEEEEE 99%); /* Opera 11.10+ */
background: -ms-linear-gradient(top, #FFFFFF 0%,#EEEEEE 99%); /* IE10+ */
}
</style>`

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