CA root certificate appears missing despite being there

[Spidersonic]

Hello,

I've been using iTLS-Enso in order to be able to display game guides in the PS Vita web browser and it used to work well.

Two days ago, I started encountering the error below while trying to access this page on Steam Community:

If I choose "Display Certificate", the following information is shown:

Via VitaShell, I've taken a look at the file "CA_LIST.cer" in "/vs0/data/external/cert/", which I installed using iTLS-Enso's latest version, and the required CA root certificate appears to be there as far as I can tell, so I don't understand where this error might be coming from.

Furthermore, if I choose to display the page anyway, it loads correctly but there's no "lock" icon shown in the URL bar:

From there, if I reload the page, I get no error and the "lock" icon properly shows up in the URL bar this time:

After further testing, this error also occurs if I try to reach Steam's homepage. It doesn't occur when trying to reach other websites, like Google or GameFAQs for instance.

Is there anything I could do to stop this error from showing up?

Any help would be greatly appreciated :)