我也遇到这问题，坑爹啊

1.把全局包升级到最新

+-- @vue/cli@4.1.1
+-- @vue/cli-service@4.1.1
+-- @vue/cli-service-global@4.1.1

2.然后把项目的cli包也配置成最新版本，终于从坑里面爬回地表了

 "dependencies": {  
    "@dcloudio/uni-app-plus": "^2.0.0-24220191115006",  
    "@dcloudio/uni-h5": "^2.0.0-24220191115006",  
    "@dcloudio/uni-helper-json": "*",  
    "@dcloudio/uni-mp-alipay": "^2.0.0-24220191115006",  
    "@dcloudio/uni-mp-baidu": "^2.0.0-24220191115006",  
    "@dcloudio/uni-mp-qq": "^2.0.0-24220191115006",  
    "@dcloudio/uni-mp-toutiao": "^2.0.0-24220191115006",  
    "@dcloudio/uni-mp-weixin": "^2.0.0-24220191115006",  
    "@dcloudio/uni-stat": "^2.0.0-24220191115006",  
    "flyio": "^0.6.14",  
    "regenerator-runtime": "^0.13.3",  
    "vue": "^2.6.10",  
    "vuex": "^3.0.1",  
  },  
  "devDependencies": {  
    "@dcloudio/uni-cli-shared": "^2.0.0-24220191115006",  
    "@dcloudio/uni-template-compiler": "^2.0.0-24220191115006",  
    "@dcloudio/vue-cli-plugin-hbuilderx": "^2.0.0-24220191115006",  
    "@dcloudio/vue-cli-plugin-uni": "^2.0.0-24220191115006",  
    "@dcloudio/vue-cli-plugin-uni-optimize": "^2.0.0-24220191115006",  
    "@dcloudio/webpack-uni-mp-loader": "^2.0.0-24220191115006",  
    "@dcloudio/webpack-uni-pages-loader": "^2.0.0-24220191115006",  
    "@types/html5plus": "^1.0.0",  
    "@types/uni-app": "^1.4.1",  
    "@vue/cli-plugin-babel": "^3.12.1",  
    "@vue/cli-service": "^3.12.1",  
    "babel-plugin-import": "^1.11.0",  
    "mini-types": "*",  
    "miniprogram-api-typings": "^2.8.0-2",  
    "node-sass": "^4.13.0",  
    "postcss-comment": "^2.0.0",  
    "sass-loader": "^8.0.0",  
    "vue-template-compiler": "^2.6.10"  
  },

找到了一个暂时的解决方案，就是降级@vue/cli-service的版本到3.x

"devDependencies": {  
    "@dcloudio/uni-cli-shared": "^2.0.0-24220191115006",  
    "@dcloudio/uni-template-compiler": "^2.0.0-24220191115006",  
    "@dcloudio/vue-cli-plugin-hbuilderx": "^2.0.0-24220191115006",  
    "@dcloudio/vue-cli-plugin-uni": "^2.0.0-24220191115006",  
    "@dcloudio/vue-cli-plugin-uni-optimize": "^2.0.0-24220191115006",  
    "@dcloudio/webpack-uni-mp-loader": "^2.0.0-24220191115006",  
    "@dcloudio/webpack-uni-pages-loader": "^2.0.0-24220191115006",  
    "@types/html5plus": "*",  
    "@types/uni-app": "*",  
    "@vue/cli-plugin-babel": "3.5.1",  
    "@vue/cli-plugin-eslint": "^4.1.0",  
-    "@vue/cli-service": "^4.1.0",  
+    "@vue/cli-service": "3.12.1",  
    "@vue/eslint-config-prettier": "^5.0.0",  
    "babel-plugin-import": "^1.11.0",  
    "eslint": "^5.16.0",  
    "eslint-plugin-prettier": "^3.1.1",  
    "eslint-plugin-vue": "^5.0.0",  
    "less": "^3.10.3",  
    "less-loader": "^5.0.0",  
    "mini-types": "*",  
    "miniprogram-api-typings": "^2.8.0-2",  
    "postcss-comment": "^2.0.0",  
    "prettier": "^1.19.1",  
    "sass": "^1.23.7",  
    "sass-loader": "^8.0.0",  
    "vue-template-compiler": "^2.6.10"  
  },

mark

接触uni-app第一个坑；

rpx在h5不能被转换识别

一般发生在cli生成的项目中；

方法一：如果是@vue/cli生成的项目，请留意 @vue/cli 与 @vue/cli-service 是否在同一个主版本号，不匹配会导致无法转换；

方法二：cli生成的项目，导入src录到hbuilderx中，启动h5查看一般是正常的；

一句话：依赖不统一，目前 @vue/cli 4.0以后版本在beta中，暂时不升级，全部降低到3.0；

2019-12-19日，npm update 更新最新版以后，问题已解决了

{  
    "@dcloudio/uni-cli-shared": "^2.0.0-24220191115011",  
    "@dcloudio/uni-template-compiler": "^2.0.0-24220191115011",  
    "@dcloudio/vue-cli-plugin-hbuilderx": "^2.0.0-24220191115011",  
    "@dcloudio/vue-cli-plugin-uni": "^2.0.0-24220191115011",  
    "@dcloudio/vue-cli-plugin-uni-optimize": "^2.0.0-24220191115011",  
    "@dcloudio/webpack-uni-mp-loader": "^2.0.0-24220191115011",  
    "@dcloudio/webpack-uni-pages-loader": "^2.0.0-24220191115011",  
}