Cannot save mail or template

Hi, I’m creating the newsletter for march but I cannot save it or proceed to next steps (scheduling).
When I press SAVE button, message “saved” appears but the changes are not really saved.
If iI try to save the works as template or try to export it, I get a “cannto save” message.
Everything worked fine last month.
Recently, my site was updated to last WordPress version.
I don’t use last WordPress Editor.

Any idea about what prevent Mailpoet to save it/proceeed to the next step?

Thanks in advance
Ferruccio

These are my data:
`name: fmanclossi
email: fmanclossi@fmanclossi.com
PHP version: 5.6.40
MailPoet Free version: 3.22.0
MailPoet Premium version: N/A
MailPoet Premium/MSS key:
WordPress version: 5.1.1
Database version: 5.6.40-84.0-log
Web server: Apache
Server OS: Linux it20.siteground.eu 3.12.18-clouder0 #1 SMP Tue Oct 9 18:14:47 EEST 2018 x86_64
WP_MEMORY_LIMIT: 128M
WP_MAX_MEMORY_LIMIT: 768M
WP_DEBUG: false
PHP max_execution_time: 120
PHP memory_limit: 768M
PHP upload_max_filesize: 128M
PHP post_max_size: 128M
WordPress language: it_IT
Multisite environment?: No
Current Theme: Writers (version 4.2)
Active Plugin names: query-monitor/query-monitor.php, above-the-fold-optimization/abovethefold.php, akismet/akismet.php, allow-epub-and-mobi-formats-upload/allow-epub-and-mobi-formats-upload.php, amp/amp.php, better-click-to-tweet/better-click-to-tweet.php, classic-editor/classic-editor.php, conversation-watson/watson.php, cookie-notice/cookie-notice.php, creative-commons-generator/ccg-init.php, custom-404-pro/custom-404-pro.php, display-posts-shortcode/display-posts-shortcode.php, edit-flow/edit_flow.php, export-to-text/export-to-text.php, far-future-expiry-header/far-future-expiration.php, getty-images/getty-images.php, glue-for-yoast-seo-amp/yoastseo-amp.php, grand-media/grand-media.php, heartbeat-control/heartbeat-control.php, imdb-info-box/imdbinfobox.php, jetpack-addons-public-related-posts/jeherve-fix-jp-related.php, jetpack/jetpack.php, limit-login-attempts/limit-login-attempts.php, mailpoet/mailpoet.php, postie/postie.php, related-posts-thumbnails/related-posts-thumbnails.php, rrssb-for-wp/rrssb-for-wp.php, social-networks-auto-poster-facebook-twitter-g/NextScripts_SNAP.php, telegram-for-wp/twp.php, tiny-compress-images/tiny-compress-images.php, tinymce-advanced/tinymce-advanced.php, tweet-old-post/tweet-old-post.php, ultimate-category-excluder/ultimate-category-excluder.php, updraftplus/updraftplus.php, wbounce/wbounce.php, wordfence/wordfence.php, wordpress-css-optimization/css-optimization.php, wordpress-html-optimization/html-optimization.php, wordpress-javascript-optimization/javascript-optimization.php, wordpress-pwa-optimization/pwa-optimization.php, wordpress-seo/wp-seo.php, wp-disable/wpperformance.php, wp-gdpr-compliance/wp-gdpr-compliance.php, wp-inject/wpinject.php, wp-maintenance-mode/wp-maintenance-mode.php, wp-theme-optimizer/wpto.php, wysija-newsletters/index.php, youtube-speedload/youtube-speedload.php
Sending Method: PHPMail
Sending Frequency: 50 emails every 30 minutes
Task Scheduler method: WordPress
Cron ping URL: https://www.fmanclossi.com?mailpoet_router&endpoint=cron_daemon&action=ping
Default FROM address: news@fmanclossi.com
Default Reply-To address: news@fmanclossi.com
Bounce Email Address: news@fmanclossi.com
Total number of subscribers: 23
Plugin installed at: 2015-09-05 06:47:24

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