since update imovie has no transition options under 'no theme'

Adding to my earlier post, here's some diagnostic procedures to try. You have already tried deleting preferences and redownloading iMovie, but those procedures are including in the list anyway.

Updating

iMovie

To update/redownload iMovie 10, drag your

iMovie 10 app from the Applications folder into the trash, but do not empty the

trash. (You can skip that step if you had iMovie 10 on your computer before,

but deleted it.) Sign in to the app store and open your purchases folder by

clicking on your name at the bottom of the app store side bar. (NOTE: For El

Capitan and older, click on the Purchases tab at the top of the app store

screen and then sign in. Click on Purchases again to reveal your

purchases.)  You will see your purchases

displayed, including iMovie 10. Redownload/update iMovie from there. If not

successful, drag your present iMovie app out of the trash (if you moved it

there) and return it to the Applications folder.

Deleting

Preferences

Try opening iMovie while holding down the

Option and Command keys and selecting to delete preferences in the box that

appears. iMovie will open in a new library. Reopen your old library to get back

to your projects.

New Project

Try creating a new project and see if that solves it.

Safe

Mode

You could also try booting up in Safe

Mode (see Finder menu for instructions) and, after everything loads,

immediately shut down and reboot in normal mode. Then see if iMovie works

properly.

Resetting

the System Management Controller

Try resetting the System Management

Controller:

https://support.apple.com/en-us/HT201295

Resetting the NVRAM or PRAM

Try resetting the NVRAM or PRAM,

although this issue would be fairly rare:

https://support.apple.com/en-us/HT204063

We have been seeing some rather odd glitches reported here after the iMovie 10.1.15 update. Your absence of transitions might be a glitch with the download or possibly a corrupt preference that can happen with new downloads.

Try opening iMovie while holding down the Option and Command keys and selecting to delete preferences in the box that

appears. iMovie will open in a new library. Reopen your old library to get back to your projects. No see if your transitions appear.

If still no luck, try redownloading iMovie. To update/redownload iMovie 10, drag your iMovie 10 app from the Applications folder into the trash, but do not empty the trash. Sign in to the app store and open your purchases folder by clicking on your name at the bottom of the app store side bar. You will see your purchases displayed, including iMovie 10. Redownload/update iMovie from there. If not successful, drag your present iMovie app out of the trash and return it to the Applications folder.

-- Rich

I also have this issue, I have tried everything above but I cannot get it to work. My laptop is a bit older, so it works so slow.

Is there anything else to suggest?

I've uninstalled, but when I try to downloading from the App Store it gets stuck and never completes. So I reinstalled it from the trash bin and the issue is still there.

I also have this issue, I have tried everything above but I cannot get it to work. My laptop is a bit older, so it works so slow.

Is there anything else to suggest?

I've uninstalled, but when I try to downloading from the App Store it gets stuck and never completes. So I reinstalled it from the trash bin and the issue is still there.

Great! Thanks for posting back as it may help others with similar problems.

-- Rich

I'm facing the same issue! Transitions are not there anymore!! Please update the app to fix this glitch.

It is an issue that Apple will need to fix. Other than the diagnostic procedures that I mentioned above, the only other things that I can think of is to try opening iMovie in your Mac's Guest account, or to use a Time Machine backup to restore your previously used version of iMovie.

-- Rich