Audio units are a game changer, the uptake from synth makers is a little slow since Aturia got the ball rolling with iSem. Last time I checked there were only two or three other synths in this format. Apparently it's difficult to implement into iOS synths, so for now we'll just have to be patient.
I've had the same issue using iSem as an AU plugin in cubasis(recently AU enabled) it seems the only way to use iSem's arp in time is to use it as an inter-app plugin. It seems to be a bug alight. Hopefully the next update will sort it out.
You load it by selecting it from the available swipe list after choosing add instrument in the usual way. There's a new AU icon available next to the inter- app audio icon. Not sure if it's available on all iPads though.
Great stuff! Works perfectly in time using garageband's own onboard arpeggiator. I hadn't thought of trying it that way so thanks for the tip! Also well done to Arturia for taking the initiative to be the first to bring The AU format to iOS, I love iSem and was delighted to see it ready for AU.
Have you activated the GB keyboard arp? You can see a little "step" symbol right of the "SKALA" button above the keys. Click on it and activate the arp by switching "Start". I've just encountered this a minute ago for myself
Anyone notice when using isem as an au plugin in GarageBand, the arp onboard isem drags in time to garagebands own tempo. I can't seem to get the two in sync with each other on my iPad Air 2. Am I missing something?