It seems that Apple did a little squeak when talking about the full support of old straps from the new Apple Watch Series 4.
The manufacturer of premium straps JUUK reported that the Kupertinovs reworked the slot for installing straps. It is recessed by 0.6 mm, and this is seen in the pictures below.
When installing some old straps, a gap will be formed. Consequently, the bracelets will stagger and not very securely hold.
Manufacturers will take time to prepare their creations under the Apple Watch Series 4. And we, in turn, recommend a little wait for the release of the updated straps. [ JUUK ]