Error: Invalid Parameter in AddToHiddenTags()

[sid]

On refind v0.14.2:

I've been using refind for quite a while. Thanks for your efforts.

I used the "-" (minus) to hide entries in tbe refind menu, which was working fine. All of a sudden the minus didn't work and shows the following error:

Error: Invalid Parameter in AddToHiddenTags()

I looked into the following code, however I don't know how to debug in refind.

// Add PathName to the hidden tags variable specified by *VarName.
static VOID AddToHiddenTags(CHAR16 *VarName, CHAR16 *Pathname) {
    CHAR16      *HiddenTags;
    EFI_STATUS  Status;

    if (Pathname && (StrLen(Pathname) > 0)) {
        HiddenTags = ReadHiddenTags(VarName);
        MergeStrings(&HiddenTags, Pathname, L',');
        Status = EfivarSetRaw(&RefindGuid, VarName, (CHAR8 *) HiddenTags, StrLen(HiddenTags) * 2 + 2, TRUE);
        CheckError(Status, L"in AddToHiddenTags()");
        MyFreePool(HiddenTags);
    } // if
} // VOID AddToHiddenTags()