The display of zig-zag or double-arrow is a rule reserved for ANSI/ASME standard dimensions. There is a document property that controls their display.
ISO dimensions do not allow for these symbols because this would be a deviation from the ISO standard. That said, SOLIDWORKS strives to support the standards, but we also wish to fulfill customer needs, even when these deviate from the standards. If you wish to use these symbols with ISO, we do have an open Enhancement Request for which you can vote. To avoid my influence having an impact on our Enhancement Request database, I typically do not post SPR numbers directly in the forum. However, if you wish, you can look up open SPRs in your Customer Portal via the Enhancement Request area and vote for any you find there.