For a mistake I did check the "hide" option of an instrument in the plugin manager. Can't manage now to reverse this situation. Thanks in advance for your help.
There's a big button called "Show Hidden" at the bottom of that window
Press that and then click on the white dot in the Hide strip to unhide the plugin.
Your subscriptions & donations are critical help that make it possible for full-time development of Ardour to continue. Your support is critical and much appreciated.
May goal US$8100 (US$97.2k/yr)
Total till now: US$6710.19
Subscribers 4023 US$9750.00/month
Support Ardour, get free upgrades: pay $1, $4, $10 or $50/month: